Camera-based tracking and authorization extension system

ABSTRACT

A system that integrates camera images and quantity sensors to determine items taken from, placed on, or moved on a shelf or other area in an autonomous store. The items and actions performed may then be attributed to a shopper near the area. Shelves may be divided into storage zones, such as bins or lanes, and a quantity sensor may measure the item quantity in each zone. Quantity changes indicate that a shopper has taken or placed items in the zone. Distance sensors, such as LIDAR, may be used for shelves that push items towards the front. Strain gauges may be used for bins or hanging rods. Quantity changes may trigger analysis of camera images of the shelf to identify the items taken or replaced. Images from multiple cameras that view a shelf may be projected to a vertical plane at the front of the shelf to simplify analysis.

This application is a continuation of U.S. Utility patent applicationSer. No. 16/513,509, filed 16 Jul. 2019, issued as U.S. Pat. Ser. No.10,586,208, which is a continuation-in-part of U.S. Utility patentapplication Ser. No. 16/404,667, filed 6 May 2019, issued as U.S. Pat.Ser. No. 10,535,146, which is a continuation-in-part of U.S. Utilitypatent application Ser. No. 16/254,776, filed 23 Jan. 2019, issued asU.S. Pat. Ser. No. 10,282,852, which is a continuation-in-part of U.S.Utility patent application Ser. No. 16/138,278, filed 21 Sep. 2018,issued as U.S. Pat. Ser. No. 10,282,720, which is a continuation-in-partof U.S. Utility patent application Ser. No. 16/036,754, filed 16 Jul.2018, issued as U.S. Pat. Ser. No. 10,373,322, the specifications ofwhich are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

One or more embodiments of the invention are related to the fields ofimage analysis, artificial intelligence, automation, camera calibration,camera placement optimization and computer interaction with a point ofsale system. More particularly, but not by way of limitation, one ormore embodiments of the invention enable a camera-based system thatanalyzes images from multiple cameras to track items in an autonomousstore, such as products on store shelves, and to determine which itemsshoppers have taken, moved, or replaced. One or more embodimentsutilizes quantity sensors that measure or infer a quantity of a productin combination with image analysis to increase accuracy of attributionof items with shoppers. Image analysis may also be used to infer thetype of a product based on the visual appearance.

Description of the Related Art

Previous systems involving security cameras have had relatively limitedpeople tracking, counting, loiter detection and object tamperinganalytics. These systems employ relatively simple algorithms that havebeen utilized in cameras and NVRs (network video recorders).

Other systems such as retail analytics solutions utilize additionalcameras and sensors in retail spaces to track people in relativelysimple ways, typically involving counting and loiter detection.

Currently there are initial “grab-n-go” systems that are in the initialprototyping phase. These systems are directed at tracking people thatwalk into a store, take what they want, put back what they don't wantand get charged for what they leave with. These solutions generally useadditional sensors and/or radio waves for perception, while othersolutions appear to be using potentially uncalibrated cameras ornon-optimized camera placement. For example, some solutions may useweight sensors on shelves to determine what products are taken from ashelf; however, these weight sensors alone are not sufficient toattribute the taking of a product with a particular shopper, or theidentity of a product from other products of similar mass or shape (forexample, different brands of soda cans may have the same geometry andmass). To date all known camera-based grab-n-go companies utilizealgorithms that employ the same basic software and hardware buildingblocks, drawing from academic papers that address parts of the overallproblem of people tracking, action detection, object recognition.

Academic building blocks utilized by entities in the automated retailsector include a vast body of work around computer vision algorithms andopen source software in this space. The basic available toolkits utilizedeep learning, convolutional neural networks, object detection, cameracalibration, action detection, video annotation, particle filtering andmodel-based estimation.

To date, none of the known solutions or systems enable a truly automatedstore and require additional sensors, use more cameras than arenecessary, do not integrate with existing cameras within a store, forexample security cameras, thus requiring more initial capital outlay. Inaddition, known solutions may not calibrate the cameras, allow forheterogenous camera types to be utilized or determine optimal placementfor cameras, thus limiting their accuracy.

For an automated store or similar applications, it may be valuable toallow a customer to obtain an authorization at an entry point or atanother convenient location, and then extend this authorizationautomatically to other locations in the store or site. For example, acustomer of an automated gas station may provide a credit card at a gaspump to purchase gas, and then enter an automated convenience store atthe gas station to purchase products; ideally the credit cardauthorization obtained at the gas pump would be extended to theconvenience store, so that the customer could enter the store (possiblythrough a locked door that is automatically unlocked for this customer),and take products and have them charged to the same card.

Authorization systems integrated into entry control systems are known inthe art. Examples include building entry control systems that require aperson to present a key card or to enter an access code. However, thesesystems do not extend the authorization obtained at one point (the entrylocation) to another location. Known solutions to extend authorizationfrom one location to additional locations generally require that theuser present a credential at each additional location whereauthorization is needed. For example, guests at events or on cruiseships may be given smart wristbands that are linked to a credit card oraccount; these wristbands may be used to purchase additional products orto enter locked areas. Another example is the system disclosed in U.S.Pat. No. 6,193,154, “Method and apparatus for vending goods inconjunction with a credit card accepting fuel dispensing pump,” whichallows a user to be authorized at a gas pump (using a credit card), andto obtain a code printed on a receipt that can then be used at adifferent location to obtain goods from a vending machine. A potentiallimitation of all of these known systems is that additional devices oractions by the user are required to extend authorization from one pointto another. There are no known systems that automatically extendauthorization from one point (such as a gas pump) to another point (suchas a store or vending machine) using only tracking of a user from thefirst point to the second via cameras. Since cameras are widelyavailable and often are already installed in sites or stores, trackingusers with cameras to extend authorization from one location to anotherwould add significant convenience and automation without burdening theuser with codes or wristbands and without requiring additional sensorsor input devices.

Another limitation of existing systems for automated stores is thecomplexity of the person tracking approaches. These systems typicallyuse complex algorithms that attempt to track joints or landmarks of aperson based on multiple camera views from arbitrary camera locations.This approach may be error-prone, and it requires significant processingcapacity to support real-time tracking. A simpler person trackingapproach may improve robustness and efficiency of the tracking process.

An automated store needs to track both shoppers moving through the storeand items in the store that shoppers may take for purchase. Existingmethods for tracking items such as products on store shelves eitherrequire dedicated sensors associated with each item, or they use imageanalysis to observe the items in a shopper's hands. The dedicated sensorapproach requires potentially expensive hardware on every store shelf.The image analysis methods used to date are error-prone. Image analysisis attractive because cameras are ubiquitous and inexpensive, requiringno moving parts, but to date image analysis of item movement from (orto) store shelves has been ineffective. In particular, simple imageanalysis methods such as image differencing from single camera views arenot able to handle occlusions well, nor are they able to determine thequantity of items taken for example from a vertical stack of similarproducts.

For at least the limitations described above there is a need for aprojected image item tracking system.

BRIEF SUMMARY OF THE INVENTION

One or more embodiments described in the specification are related toprojected image item tracking system, for example as used in anautomated store system that combines projected images to track items.One or more embodiments include a processor that is configured to obtaina 3D model of a store that contains items and item storage areas. Theprocessor receives a respective time sequence of images from cameras inthe store, wherein the time sequence of images is captured over a timeperiod and analyzes the time sequence of images from each camera and the3D model of the store to detect a person in the store based on the timesequence of images, calculate a trajectory of the person across the timeperiod, identify an item storage area of the item storage areas that isproximal to the trajectory of the person during an interaction timeperiod within the time period, analyze two or more images of the timesequence of images to identify an item of the items within the itemstorage area that moves during the interaction time period, wherein thetwo or more images are captured within or proximal in time to theinteraction time period and the two or more images contain views of theitem storage area and attribute motion of the item to the person. One ormore embodiments of the system rely on images for tracking and do notutilize item tags, for example RFID tags or other identifiers on theitems that are manipulated and thus do not require identifier scanners.In addition, one or more embodiments of the invention enable a “virtualdoor” where entry and exit of users triggers a start or stop of thetracker, i.e., via images and computer vision. Other embodiments mayutilize physical gates or electronic check-in and check-out, e.g., usingQR codes or Bluetooth, but these solutions add complexity that otherembodiments of the invention do not require.

At least one embodiment of the processor is further configured tointerface with a point of sale computer and charge an amount associatedwith the item to the person without a cashier. Optionally, a descriptionof the item is sent to a mobile device associated with the person andwherein the processor or point of sale computer is configured to accepta confirmation from the mobile device that the item is correct or indispute. In one or more embodiments, a list of the items associated witha particular user, for example a shopping cart list associated with theshopper, may be sent to a display near the shopper or that is closest tothe shopper.

In one or more embodiments, each image of the time sequence of images isa 2D image and the processor calculates a trajectory of the personconsisting of a 3D location and orientation of the person and at leastone body landmark from two or more 2D projections of the person in thetime sequence of images.

In one or more embodiments, the processor is further configured tocalculate a 3D field of influence volume around the person at points oftime during the time period.

In one or more embodiments, the processor identifies an item storagearea that is proximal to the trajectory of the person during aninteraction time period utilizes a 3D location of the storage area thatintersects the 3D field of influence volume around the person during theinteraction time period. In one or more embodiments, the processorcalculates the 3D field of influence volume around the person utilizinga spatial probability distribution for multiple landmarks on the personat the points of time during the time period, wherein each landmark ofthe multiple landmarks corresponds to a location on a body part of theperson. In one or more embodiments, the 3D field of influence volumearound the person comprises points having a distance to a closestlandmark of the multiple landmarks that is less than or equal to athreshold distance. In one or more embodiments, the 3D field ofinfluence volume around the person comprises a union of probable zonesfor each landmark of the multiple landmarks, wherein each probable zoneof the probable zones contains a threshold probability of the spatialprobability distribution for a corresponding landmark. In one or moreembodiments, the processor calculates the spatial probabilitydistribution for multiple landmarks on the person at the points of timeduring the time period through calculation of a predicated spatialprobability distribution for the multiple landmarks at one or morepoints of time during the time period based on a physics model andcalculation of a corrected spatial probability distribution at one ormore points of time during the time period based on observations of oneor more of the multiple landmarks in the time sequence of images. In oneor more embodiments, the physics model includes the locations andvelocities of the landmarks and thus the calculated field of influence.This information can be used to predict a state of landmarks associatedwith a field at a time and a space not directly observed and thus may beutilized to interpolate or augment the observed landmarks.

In one or more embodiments, the processor is further configured toanalyze the two or more images of the time sequence of images toclassify the motion of the item as a type of motion comprising taking,putting or moving.

In one or more embodiments, the processor analyzes two or more images ofthe time sequence of images to identify an item within the item storagearea that moves during the interaction time period. Specifically, theprocessor uses or obtains a neural network trained to recognize itemsfrom changes across images, sets an input layer of the neural network tothe two or more images and calculates a probability associated with theitem based on an output layer of the neural network. In one or moreembodiments, the neural network is further trained to classify an actionperformed on an item into classes comprising taking, putting, or moving.In one or more embodiments, the system includes a verification systemconfigured to accept input confirming or denying that the person isassociated with motion of the item. In one or more embodiments, thesystem includes a machine learning system configured to receive theinput confirming or denying that the person is associated with themotion of the item and updates the neural network based on the input.Embodiments of the invention may utilize a neural network or moregenerally, any type of generic function approximator. By definition thefunction to map inputs of before-after image pairs, orbefore-during-after image pairs to output actions, then the neuralnetwork can be trained to be any such function map, not just traditionalconvolutional neural networks, but also simpler histogram or featurebased classifiers. Embodiments of the invention also enable training ofthe neural network, which typically involves feeding labeled data to anoptimizer that modifies the network's weights and/or structure tocorrectly predict the labels (outputs) of the data (inputs). Embodimentsof the invention may be configured to collect this data from customer'sacceptance or correction of the presented shopping cart. Alternatively,or in combination, embodiments of the system may also collect humancashier corrections from traditional stores. After a user accepts ashopping cart or makes a correction, a ground truth labeled data pointmay be generated and that point may be added to the training set andused for future improvements.

In one or more embodiments, the processor is further configured toidentify one or more distinguishing characteristics of the person byanalyzing a first subset of the time sequence of images and recognizesthe person in a second subset of the time sequence of images using thedistinguishing characteristics. In one or more embodiments, theprocessor recognizes the person in the second subset withoutdetermination of an identity of the person. In one or more embodiments,the second subset of the time sequence of images contains images of theperson and images of a second person. In one or more embodiments, theone or distinguishing characteristics comprise one or more of shape orsize of one or more body segments of the person, shape, size, color, ortexture of one or more articles of clothing worn by the person and gaitpattern of the person.

In one or more embodiments of the system, the processor is furtherconfigured to obtain camera calibration data for each camera of thecameras in the store and analyze the time sequence of images from eachcamera of the cameras using the camera calibration data. In one or moreembodiments, the processor configured to obtain calibration images fromeach camera of the cameras and calculate the camera calibration datafrom the calibration images. In one or more embodiments, the calibrationimages comprise images captured of one or more synchronization eventsand the camera calibration data comprises temporal offsets among thecameras. In one or more embodiments, the calibration images compriseimages captured of one or markers placed in the store at locationsdefined relative to the 3D model and the camera calibration datacomprises position and orientation of the cameras with respect to the 3Dmodel. In one or more embodiments, the calibration images compriseimages captured of one or more color calibration targets located in thestore, the camera calibration data comprises color mapping data betweeneach camera of the cameras and a standard color space. In one or moreembodiments, the camera calibration processor is further configured torecalculate the color mapping data when lighting conditions change inthe store. For example, in one or more embodiments, different cameracalibration data may be utilized by the system based on the time of day,day of year, current light levels or light colors (hue, saturation orluminance) in an area or entire image, such as occur at dusk or dawncolor shift periods. By utilizing different camera calibration data, forexample for a given camera or cameras or portions of images from acamera or camera, more accurate determinations of items and theirmanipulations may be achieved.

In one or more embodiments, any processor in the system, such as acamera placement optimization processor is configured to obtain the 3Dmodel of the store and calculate a recommended number of the cameras inthe store and a recommended location and orientation of each camera ofthe cameras in the store. In one or more embodiments, the processorcalculates a recommended number of the cameras in the store and arecommended location and orientation of each camera of the cameras inthe store. Specifically, the processor obtains a set of potential cameralocations and orientations in the store, obtains a set of item locationsin the item storage areas and iteratively updates a proposed number ofcameras and a proposed set of camera locations and orientations toobtain a minimum number of cameras and a location and orientation foreach camera of the minimum number of cameras such that each itemlocation of the set of item locations is visible to at least two of theminimum number of cameras.

In one or more embodiments, the system comprises the cameras, whereinthe cameras are coupled with the processor. In other embodiments, thesystem includes any subcomponent described herein.

In one or more embodiments, processor is further configured to detectshoplifting when the person leaves the store without paying for theitem. Specifically, the person's list of items on hand (e.g., in theshopping cart list) may be displayed or otherwise observed by a humancashier at the traditional cash register screen. The human cashier mayutilize this information to verify that the shopper has either not takenanything or is paying/showing for all items taken from the store. Forexample, if the customer has taken two items from the store, thecustomer should pay for two items from the store. Thus, embodiments ofthe invention enable detection of customers that for example take twoitems but only show and pay for one when reaching the register.

In one or more embodiments, the computer is further configured to detectthat the person is looking at an item.

In one or more embodiments, the landmarks utilized by the systemcomprise eyes of the person or other landmarks on the person's head, andwherein the computer is further configured to calculate a field of viewof the person based on a location of the eyes or other head landmarks ofthe person, and to detect that the person is looking at an item when theitem is in the field of view.

One or more embodiments of the system may extend an authorizationobtained at one place and time to a different place or a different time.The authorization may be extended by tracking a person from the point ofauthorization to a second point where the authorization is used. Theauthorization may be used for entry to a secured environment, and topurchase items within this secured environment.

To extend an authorization, a processor in the system may analyze imagesfrom cameras installed in or around an area in order to track a personin the area. Tracking may also use a 3D model of the area, which may forexample describe the location and orientation of the cameras. Theprocessor may calculate the trajectory of the person in the area fromthe camera images. Tracking and calculation of the trajectory may useany of the methods described above or described in detail below.

The person may present a credential, such as a credit card, to acredential receiver, such as a card reader, at a first location and at afirst time, and may then receive an authorization; the authorization mayalso be received by the processor. The person may then move to a secondlocation at a second time. At this second location, an entry to asecured environment may be located, and the entry may be secured by acontrollable barrier such as a lock. The processor may associate theauthorization with the person by relating the time that the credentialwas presented, or the authorization was received, with the time that theperson was at the first location where the credential receiver islocated. The processor may then allow the person to enter the securedenvironment by transmitting an allow entry command to the controllablebarrier when the person is at the entry point of the securedenvironment.

The credential presented by the person to obtain an authorization mayinclude for example, without limitation, one or more of a credit card, adebit card, a bank card, an RFID tag, a mobile payment device, a mobilewallet device, an identity card, a mobile phone, a smart phone, a smartwatch, smart glasses or goggles, a key fob, a driver's license, apassport, a password, a PIN, a code, a phone number, or a biometricidentifier.

In one or more embodiments the secured environment may be all or portionof a building, and the controllable barrier may include a door to thebuilding or to a portion of the building. In one or more embodiments thesecured environment may be a case that contains one or more items (suchas a display case with products for sale), and the controllable barriermay include a door to the case.

In one or more embodiments, the area may be a gas station, and thecredential receiver may be a payment mechanism at or near a gas pump.The secured environment may be for example a convenience store at thegas station or a case (such as a vending machine for example) at the gasstation that contains one or more items. A person may for example pay atthe pump and obtain an authorization for pumping gas and for enteringthe convenience store or the product case to obtain other products.

In one or more embodiments, the credential may be or may include a formof payment that is linked to an account of the person with thecredential, and the authorization received by the system may be anauthorization to charge purchases by the person to this account. In oneor more embodiments, the secured environment may contain sensors thatdetect when one or more items are taken by the person. Signals from thesensors may be received by the system's processor and the processor maythen charge the person's account for the item or items taken. In one ormore embodiments the person may provide input at the location where heor she presents the credential that indicates whether to authorizepurchases of items in the secured environment.

In one or more embodiments, tracking of the person may also occur in thesecured environment, using cameras in the secured environment. Asdescribed above with respect to an automated store, tracking maydetermine when the person is near an item storage area, and analysis oftwo or more images of the item storage area may determine that an itemhas moved. Combining these analyses allows the system to attributemotion of an item to the person, and to charge the item to the person'saccount if the authorization is linked to a payment account. Again asdescribed with respect to an automated store, tracking and determiningwhen a person is at or near an item storage area may include calculatinga 3D field of influence volume around the person; determining when anitem is moved or taken may use a neural network that inputs two or moreimages (such as before and after images) of the item storage area andoutputs a probability that an item is moved.

In one or more embodiments, an authorization may be extended from oneperson to another person, such as another person who is in the samevehicle as the person with the credential. The processor may analyzecamera images to determine that one person exits a vehicle and thenpresents a credential, resulting in an authorization. If a second personexits the same vehicle, that second person may also be authorized toperform certain actions, such as entering a secured area or taking itemsthat will be charge to the account associated with the credential.Tracking the second person and determining what items that person takesmay be performed as described above for the person who presents thecredential.

In one or more embodiments, extension of an authorization may enable aperson who provides a credential to take items and have them charged toan account associated with the credential; the items may or may not bein a secured environment having an entry with a controllable barrier.Tracking of the person may be performed using cameras, for example asdescribed above. The system may determine what item or items the persontakes by analyzing camera images, for example as described above. Theprocessor associated with the system may also analyze camera images todetermine when a person takes and item and then puts the item down priorto leaving an area; in this case the processor may determine that theperson should not be charged for the item when leaving the area.

One or more embodiments of the invention may analyze camera images tolocate a person in the store, and may then calculate a field ofinfluence volume around the person. This field of influence volume maybe simple or detailed. It may be a simple shape, such as a cylinder forexample, around a single point estimate of a person's location. Trackingof landmarks or joints on the person's body may not be needed in one ormore embodiments. When the field of influence volume intersects an itemstorage area during an interaction period, the system may analyze imagescaptured at the beginning of this period or before, and images capturedat the end of this period or afterwards. This analysis may determinewhether an item on the shelf has moved, in which case this movement maybe attributed to the person whose field of influence volume intersectedthe item storage area. Analysis of before and after images may be donefor example using a neural network that takes these two images as input.The output of the neural network may include probabilities that eachitem has moved, and probabilities associated with each action of a setof possible actions that a person may have taken (such as for exampletaking, putting, or moving an item). The item and action with thehighest probabilities may be selected and may be attributed to theperson that interacted with the item storage area.

In one or more embodiments the cameras in a store may include ceilingcameras mounted on the store's ceiling. These ceiling cameras may befisheye cameras, for example. Tracking people in the store may includeprojecting images from ceiling cameras onto a plane parallel to thefloor, and analyzing the projected images.

In one or more embodiments the projected images may be analyzed bysubtracting a store background image from each, and combining thedifferences to form a combined mask. Person locations may be identifiedas high intensity locations in the combined mask.

In one or more embodiments the projected images may be analyzed byinputting them into a machine learning system that outputs an intensitymap that contains a likelihood that a person is at each location. Themachine learning system may be a convolutional neural network, forexample. An illustrative neural network architecture that may be used inone or more embodiments is a first half subnetwork consisting of copiesof a feature extraction network, one copy for each projected image, afeature merging layer that combines outputs from the copies of thefeature extraction network, and a second half subnetwork that mapscombined features into the intensity map.

In one or more embodiments, additional position map inputs may beprovided to the machine learning system. Each position map maycorrespond to a ceiling camera. The value of the position map at eachlocation may a function of the distance between the location and theceiling camera. Position maps may be input into a convolutional neuralnetwork, for example as an additional channel associated with eachprojected image.

In one or more embodiments the tracked location of a person may be asingle point. It may be a point on a plane, such as the plane parallelto the floor onto which ceiling camera images are projected. In one ormore embodiments the field of influence volume around a person may be atranslated copy of a standardized shape, such as a cylinder for example.

One or more embodiments may include one or more modular shelves. Eachmodular shelf may contain at least one camera module on the bottom ofthe shelf, at least one lighting module on the bottom of the shelf, aright-facing camera on or near the left edge of the shelf, a left-facingcamera on or near the right edge of the shelf, a processor, and anetwork switch. The camera module may contain two or moredownward-facing cameras.

Modular shelves may function as item storage areas. The downward-facingcameras in a shelf may view items on the shelf below.

The position of camera modules and lighting modules in a modular shelfmay be adjustable. The modular shelf may have a front rail and back railonto which the camera and lighting modules may be mounted and adjusted.The camera modules may have one or more slots into which thedownward-facing cameras are attached. The position of thedownward-facing cameras in the slots may be adjustable.

One or more embodiments may include a modular ceiling. The modularceiling may have a longitudinal rail mounted to the store's ceiling, andone or more transverse rails mounted to the longitudinal rail. Theposition of each transverse rail along the longitudinal rail may beadjustable. One or more integrated lighting-camera modules may bemounted to each transverse rail. The position of each integratedlighting-camera module may be adjustable along the transverse rail. Anintegrated lighting-camera module may include a lighting elementsurrounding a center area, and two or more ceiling cameras mounted inthe center area. The ceiling cameras may be mounted to a camera modulein the center area with one or more slots into which the cameras aremounted; the positions of the cameras in the slots may be adjustable.

One or more embodiments of the invention may track items in an itemstorage area by combining projected images from multiple cameras. Thesystem may include a processor coupled to a sensor that detects when ashopper reaches into or retracts from an item storage area. The sensormay generate an enter signal when it detects that the shopper hasreached into or towards the item storage area, and it may generate anexit signal when it detects that the shopper has retracted from the itemstorage area. The processor may also be coupled to multiple cameras thatview the item storage area. The processor may obtain “before” imagesfrom each of the cameras that were captured before the enter signal, and“after” images from each of the cameras that were captured after theexit signal. It may project all of these images onto multiple planes inthe item storage area. It may analyze the projected before images andthe projected after images to identify an item taken from or put intothe item storage are between the enter signal and the exit signal, andto associate this item with the shopper who interacted with the itemstorage area.

Analyzing the projected before images and the projected after images mayinclude calculating a 3D volume difference between the contents of theitem storage area before the enter signal and the contents of the itemstorage area after the exit signal. When the 3D volume differenceindicates that contents are smaller after the exit signal, the systemmay input all or a portion of one of the projected before images into aclassifier. When the 3D volume difference indicates that contents aregreater after the exit signal, the system may input all or a portion ofone of the projected after images into the classifier. The output of theclassifier may be used as the identity of the item (or items) taken fromor put into the item storage area. The classifier may be for example aneural network trained to recognize images of the items.

The processor may also calculate the quantity of items taken from or putinto the item storage area from the 3D volume difference, and associatethis quantity with the shopper. For example, the system may obtain thesize of the item (or items) identified by the classifier, and comparethis size to the 3D volume difference to calculate the quantity.

The processor may also associate an action with the shopper and the itembased on whether the 3D volume difference indicates that the contents ofthe item storage area is smaller or larger after the interaction: if thecontents are larger, then the processor may associate a put action withthe shopper, and if they are smaller, then the processor may associate atake action with the shopper.

One or more embodiments may generate a “before” 3D surface of the itemstorage area contents from projected before images, and an “after” 3Dsurface of the contents from projected after images. Algorithms such asfor example plane-sweep stereo may be used to generate these surfaces.The 3D volume difference may be calculated as the volume between thesesurfaces. The planes onto which before and after images are projectedmay be parallel to a surface of the item storage area (such as a shelf),or one or more of these planes may not be parallel to such a surface.

One or more embodiments may calculate a change region in each projectedplane, and may combine these change regions into a change volume. Thebefore 3D surface and after 3D surface may be calculated only in thechange volume. The change region of a projected plane may be calculatedby forming an image difference between each before projected image inthat plane and each after projected image in the plane, for each camera,and then combining these differences across cameras. Combining the imagedifferences across cameras may weight pixels in each difference based onthe distance between the point in the plane in that image difference andthe associated camera, and may form the combined change region as aweighted average across cameras. The image difference may be for exampleabsolute pixel differences between before and after projected images.One or more embodiments may instead input before and after images into aneural network to generate image differences.

One or more embodiments may include a modular shelf with multiplecameras observing an item storage area (for example, below the shelf),left and right-facing cameras on the edges, a shelf processor, and anetwork switch. The processor that analyzes images may be a network ofprocessors that include a store processor and the shelf processor. Theleft and right-facing cameras and the processor may provide a sensor todetect when a shopper reaches into or retracts from an item storagearea, and to generate the associated enter and exit signals. The shelfprocessor may be coupled to a memory that stores camera images; when anenter signal is received, the shelf processor may retrieve before imagesfrom this memory. The shelf processor may send the before images to astore processor for analysis. It may obtain after images from thecameras or from the memory and also send them to the store computer foranalysis.

One or more embodiments may analyze projected before images andprojected after images by inputting them or a portion of them into aneural network. The neural network may be trained to output the identityof the item or items taken from or put into the item storage areabetween the enter signal and the exit signal. It may also be trained tooutput an action that indicates whether the item is taken from or putinto the storage area. One or more embodiments may use a neural networkthat contains a feature extraction layer applied to each input mage,followed by a differencing layer that calculates feature differencesbetween each before and each corresponding after image, followed by oneor more convolutional layers, followed by an item classifier layer andan action classifier layer.

One or more embodiments may combine quantity sensors and camera imagesto detect and identify items added or removed by a shopper. A storagearea, such as a shelf, may be divided into one or more storage zones,and a quantity sensor may be associated with each zone. The quantitysignal generated by the quantity sensor may be correlated with thenumber of items in the zone. A processor or processors may analyzequantity signals to determine when and where a shopper adds or removeitems, and to determine how many items are affected. It may then obtaincamera images of the affected storage area, from before or after theshopper action. The images may be projected onto a plane in the itemstorage area, and analyzed to identify the item or items added orremoved. The item or items and the quantity change may then beassociated with the shopper who performed the action.

The plane onto which camera images are projected may be a vertical planealong or near the front face of the item storage area. Regions of theprojected images corresponding to the affected storage zone may beanalyzed to identify the items added or removed. If the quantity signalshows an increase in quantity, then the projected after images may beanalyzed; if it shows a decrease in quantity, then the projected beforeimages may be analyzed. The regions of the before and after imagescorresponding to the affected storage zone may be input into aclassifier, such as a neural network trained to identify items based ontheir images.

An illustrative storage zone may have a moveable back that moves towardsthe front of the storage zone when a shopper removes an item, and thatmoves away from the front when the shopper adds an item. The quantitysignal that measures the quantity in this type of storage zone may forexample be correlated with the position of the moveable back. Forexample, a distance sensor, such as a LIDAR or ultrasonic rangefinder,may measure the distance to the moveable back. A single-pixel LIDAR maybe sufficient to track the quantity of items in the zone.

Another illustrative storage zone may have a hanging mount from whichitems are suspended. The quantity signal associated with this zone maybe the weight of the items. This weight may be measured for example bytwo or more strain gauges.

A third illustrative storage zone may be a bin that contains item, andthe quantity sensor for this bin may be a weight scale that measures theweight of the items in the bin.

The location of a shopper's 3D field of influence volume, as determinedby tracking shoppers through a store, may be used to determine when eachcamera has an unobstructed view of the storage zone in which items areadded or removed. Camera images that are unobstructed may be used todetermine the identities of the items affected.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee.

The above and other aspects, features and advantages of the inventionwill be more apparent from the following more particular descriptionthereof, presented in conjunction with the following drawings wherein:

FIG. 1 illustrates operation of an embodiment of the invention thatanalyzes images from cameras in a store to detect that a person hasremoved a product from a shelf.

FIG. 2 continues the example shown in FIG. 1 to show automated checkoutwhen the person leaves the store with an item.

FIG. 3 shows an illustrative method of determining that an item has beenremoved from a shelf by feeding before and after images of the shelf toa neural network to detect what item has been taken, moved, or put backwherein the neural network may be implemented in one or more embodimentsof the invention through a Siamese neural network with two image inputsfor example.

FIG. 4 illustrates training the neural network shown in FIG. 3.

FIG. 4A illustrates an embodiment that allows manual review andcorrection of a detection of an item taken by a shopper and retrainingof the neural network with the corrected example.

FIG. 5 shows an illustrative embodiment that identifies people in astore based on distinguishing characteristics such as body measurementsand clothing color.

FIGS. 6A through 6E illustrate how one or more embodiments of theinvention may determine a field of influence volume around a person byfinding landmarks on the person's body and calculating an offsetdistance from these landmarks.

FIGS. 7A and 7B illustrate a different method of determining a field ofinfluence volume around a person by calculating a probabilitydistribution for the location of landmarks on a person's body andsetting the volume to include a specified amount of the probabilitydistribution.

FIG. 8 shows an illustrative method for tracking a person's movementsthrough a store, which uses a particle filter for a probabilitydistribution of the person's state, along with a physics model formotion prediction and a measurement model based on camera imageprojection observations.

FIG. 9 shows a conceptual model for how one or more embodiments maycombine tracking of a person's field of influence with detection of itemmotion to attribute the motion to a person.

FIG. 10 illustrates an embodiment that attributes item movement to aperson by intersecting the person's field of influence volume with anitem storage area, such as a shelf and feeding images of the intersectedregion to a neural network for item detection.

FIG. 11 shows screenshots of an embodiment of the system that tracks twopeople in a store and detects when one of the tracked people picks up anitem.

FIG. 12 shows screenshots of the item storage area of FIG. 11,illustrating how two different images of the item storage area may beinput into a neural network for detection of the item that was moved bythe person in the store.

FIG. 13 shows the results of the neural network classification in FIG.12, which tags the people in the store with the items that they move ortouch.

FIG. 14 shows a screenshot of an embodiment that identifies a person ina store and builds a 3D field of influence volume around the identifiedlandmarks on the person.

FIG. 15 shows tracking of the person of FIG. 14 as he moves through thestore.

FIG. 16 illustrates an embodiment that applies multiple types of cameracalibration corrections to images.

FIG. 17 illustrates an embodiment that generates camera calibration databy capturing images of markers placed throughout a store and alsocorrects for color variations due to hue, saturation or luminancechanges across the store and across time.

FIG. 18 illustrates an embodiment that calculates an optimal cameraconfiguration for a store by iteratively optimizing a cost function thatmeasures the number of cameras and the coverage of items by camerafields of view.

FIG. 19 illustrates an embodiment installed at a gas station thatextends an authorization from a card reader at a gas pump to provideautomated access to a store where a person may take products and havethem charged automatically to the card account.

FIG. 20 shows a variation of the embodiment of FIG. 19, where a lockedcase containing products is automatically unlocked when the person whopaid at a pump is at the case.

FIG. 21 continues the example of FIG. 20, showing that the productstaken by the person from the case may be tracked using cameras or othersensors and may be charged to the card account used at the pump.

FIG. 22 continues the example of FIG. 19, illustrating tracking theperson once he or she enters the store, analyzing images to determinewhat products the person has taken and charging the account associatedwith the card entered at the pump.

FIG. 23 shows a variation of the example of FIG. 22, illustratingtracking that the person picks up and then later puts down an item, sothat the item is not charged to the person.

FIG. 24 shows another variation of the example of FIG. 19, where theauthorization obtained at the pump may apply to a group of people in acar.

FIGS. 25A, 25B and 25C illustrate an embodiment that queries a user asto whether to extend authorization from the pump to purchases at a storefor the user and also for other occupants of the car.

FIGS. 26A through 26F show illustrative camera images from sixceiling-mounted fisheye cameras that may be used for tracking peoplethrough a store.

FIGS. 27A, 27B, and 27C show projections of three of the fisheye cameraimages from FIGS. 26A through 26F onto a horizontal plane one meterabove the floor.

FIGS. 28A, 28B, and 28C show binary masks of the foreground objects inFIGS. 27A, 27B, and 27C, respectively, as determined for example bybackground subtraction or motion filtering. FIG. 28D shows a compositeforeground mask that combines all camera image projections to determinethe position of people in the store.

FIGS. 29A through 29F show a cylinder generated around one of thepersons in the store, as viewed from each of the six fisheye cameras.

FIGS. 30A through 30F show projections of the six fisheye camera viewsonto the cylinders shown in FIGS. 29A through 29F, respectively. FIG.30G shows a composite of the six projections of FIGS. 30A through 30F.

FIGS. 31A and 31B show screenshots at two different points in time of anembodiment of a people tracking system using the fisheye camerasdescribed above.

FIG. 32 shows an illustrative embodiment that uses a machine learningsystem to detect person locations from camera images.

FIG. 32A shows generation of 3D or 2D fields of influence around personlocations generated by a machine learning system.

FIG. 33 illustrates projection of ceiling camera images onto a planeparallel to the floor, so that pixels corresponding to the same personlocation on this plane are aligned in the projected images.

FIGS. 34A and 34B show an artificial 3D scene that is used in FIGS. 35through 41 to illustrate embodiments of the invention that use projectedimages and machine learning for person detection.

FIG. 35 shows fisheye camera images captured by the ceiling cameras inthe scene.

FIG. 36 shows the fisheye camera images of FIG. 35 projected onto acommon plane.

FIG. 37 shows the overlap of the projected images of FIG. 36,illustrating the coincidence of pixels for persons at the intersectionof the projected plane.

FIG. 38 shows an illustrative embodiment that augments projected imageswith a position weight map that reflects the distance of each point fromthe camera that captures each image.

FIG. 39 shows an illustrative machine learning system with inputs fromeach camera in a store, where each input has four channels representingthree color channels augmented with a position weight channel.

FIG. 40 shows an illustrative neural network architecture that may beused in one or more embodiments to detect persons from camera images.

FIG. 41 shows an illustrative process of generating training data for amachine learning person detection system.

FIG. 42 shows an illustrative store with modular “smart” shelves thatintegrate cameras, lighting, processing, and communication to detectmovement of items on the shelves.

FIG. 43 shows a front view of an illustrative embodiment of a smartshelf.

FIGS. 44A, 44B, and 44C show top, side, and bottom views of the smartshelf of FIG. 43.

FIG. 45 shows a bottom view of the smart shelf of FIG. 44C with theelectronics covers removed to show the components.

FIGS. 46A and 46B show bottom and side views, respectively, of a cameramodule that may be installed into the smart shelf of FIG. 45.

FIG. 47 shows a rail mounting system that may be used on the smart shelfof FIG. 45, which allows lighting and camera modules to be installed atany desired positions along the shelf.

FIG. 48 shows an illustrative store with a modular, “smart” ceilingsystem into which camera and lighting modules may be installed at anydesired positions and spacings.

FIG. 49 shows an illustrative smart ceiling system that supportsinstallation of integrated lighting-camera modules at any desiredhorizontal positions.

FIG. 50 shows a closeup view of a portion of the smart ceiling system ofFIG. 49, showing the main longitudinal rail, and a moveable transverserail onto which integrated lighting-camera modules are mounted.

FIG. 51 shows a closeup view of an integrated lighting-camera module ofFIG. 50.

FIG. 52 shows an autonomous store system with components that performthree functions: (1) tracking shoppers through the store; (2) trackingshoppers' interactions with items on a shelf; and (3) tracking movementof items on a shelf.

FIGS. 53A and 53B show an illustrative shelf of an autonomous store thata shopper interacts with to remove items from the shelf; 53B is a viewof the shelf before the shopper reaches into the shelf to take items,and 53A is a view of the shelf after this interaction.

FIG. 54 shows an illustrative flowchart for a process that may be usedin one or more embodiments to determine removal of, addition of, ormovement of items on a shelf or other storage area; this processcombines projected images from multiple cameras onto multiple surfacesto determine changes.

FIG. 55 shows components that may be used to obtain camera images beforeand after a user interaction with a shelf.

FIGS. 56A and 56B show projections of camera images onto illustrativeplanes in an item storage area.

FIG. 57A shows an illustrative comparison of “before” and “after”projected images to determine a region in which items may have beenadded or removed.

FIG. 57B shows the comparison process of FIG. 57A applied to actualimages from a sample shelf.

FIG. 58 shows an illustrative process that combines image differencesfrom multiple cameras, with weights applied to each image differencebased on the distance of each projected pixel from the respectivecamera.

FIG. 59 illustrates combining image differences in multiple projectedplanes to determine a change volume within which items may have moved.

FIG. 60 shows illustrative sweeping of the change volume with projectedimage planes before and after shopper interaction, in order to constructa 3D volume difference between shelf contents before and after theinteraction.

FIG. 61 shows illustrative plane sweeping of a sample shelf from twocameras, showing that different objects come into focus in differentplanes that correspond to the heights of those objects.

FIG. 62 illustrates identification of items using an image classifierand calculation of the quantity of items added to or removed from ashelf.

FIG. 63 shows a neural network that may be used in one or moreembodiments to identify items moved by a shopper, and the action theshopper takes on those items, such as taking from a shelf or puttingonto a shelf.

FIG. 64 shows an embodiment of the invention that combines persontracking via ceiling cameras, action detection via quantity sensorscoupled to the shelves, and item identification via store cameras.

FIG. 65 shows an architecture for illustrative sensor types that may beused to enable analyses of shopper movements and shopper actions.

FIG. 66A shows an illustrative shelf with items arranged in zones thathave moveable backs to press items towards the front of the shelf asitems are removed. Associated with each zone is a sensor that measuresthe distance to the moveable back. FIG. 66B shows a top view of theshelf of FIG. 66A.

FIG. 66C shows an illustrative modular sensor bar with sensor units thatslide along the bar to accommodate varying sizes and locations of itemstorage zones.

FIG. 66D shows an image of the modular sensor bar of FIG. 66C.

FIG. 67 shows an illustrative method for calculating the quantity ofitems in a storage zone using the distance to the moveable back as theinput data.

FIG. 68 illustrates action detection using the data from the embodimentshown in FIG. 66A.

FIG. 69A shows a different embodiment of a shelf with integratedquantity sensors; this embodiment uses hanging rods with weight sensorsto determine the quantity. FIG. 69B shows a side view of a storage zoneof the embodiment of FIG. 69B, and it illustrates calculation of thequantity of items using strain gauge sensors coupled to the hanging rod.

FIG. 70A shows another embodiment of a shelf with quantity sensors; thisembodiment uses bins with weight measurement sensors underneath thebins. FIG. 70B shows a side view of a bin from FIG. 70A.

FIG. 71 illustrates close packing of shelves using an embodiment withintegrated quantity sensors.

FIG. 72A shows illustrative data flow and processing steps when ashopper removes an item from a shelf of the embodiment of FIG. 71.

FIG. 72B shows illustrative camera images from a store that areprojected onto the front of a shelving unit so that products are in thesame positions in different projected camera images.

FIG. 73 shows a variation of the example of FIG. 72A, where the systemcombines person tracking with item tracking to determine which camera orcameras have an unoccluded view of the storage zone from which an itemwas removed.

DETAILED DESCRIPTION OF THE INVENTION

A smart shelf system that integrates images and quantity sensors, asused for example in an autonomous store system that tracks shoppers anditems, will now be described. Embodiments may track a person byanalyzing camera images and may therefore extend an authorizationobtained by this person at one point in time and space to a differentpoint in time or space. Embodiments may also enable an autonomous storesystem that analyzes camera images to track people and theirinteractions with items and may also enable camera calibration, optimalcamera placement and computer interaction with a point of sale system.The computer interaction may involve a mobile device and a point of salesystem for example. In the following exemplary description, numerousspecific details are set forth in order to provide a more thoroughunderstanding of embodiments of the invention. It will be apparent,however, to an artisan of ordinary skill that the present invention maybe practiced without incorporating all aspects of the specific detailsdescribed herein. In other instances, specific features, quantities, ormeasurements well known to those of ordinary skill in the art have notbeen described in detail so as not to obscure the invention. Readersshould note that although examples of the invention are set forthherein, the claims and the full scope of any equivalents, are whatdefine the metes and bounds of the invention.

FIG. 1 shows an embodiment of an automated store. A store may be anylocation, building, room, area, region, or site in which items of anykind are located, stored, sold, or displayed, or through which peoplemove. For example, without limitation, a store may be a retail store, awarehouse, a museum, a gallery, a mall, a display room, an educationalfacility, a public area, a lobby, an office, a home, an apartment, adormitory, or a hospital or other health facility. Items located in thestore may be of any type, including but not limited to products that arefor sale or rent.

In the illustrative embodiment shown in FIG. 1, store 101 has an itemstorage area 102, which in this example is a shelf. Item storage areasmay be of any type, size, shape and location. They may be of fixeddimensions or they may be of variable size, shape, or location. Itemstorage areas may include for example, without limitation, shelves,bins, floors, racks, refrigerators, freezers, closets, hangers, carts,containers, boards, hooks, or dispensers. In the example of FIG. 1,items 111, 112, 113 and 114 are located on item storage area 102.Cameras 121 and 122 are located in the store and they are positioned toobserve all or portions of the store and the item storage area. Imagesfrom the cameras are analyzed to determine the presence and actions ofpeople in the store, such as person 103 and in particular to determinethe interactions of these people with items 111-114 in the store. In oneor more embodiments, camera images may be the only input required orused to track people and their interactions with items. In one or moreembodiments, camera image data may be augmented with other informationto track people and their interactions with items. One or moreembodiments of the system may utilize images to track people and theirinteractions with items for example without the use of anyidentification tags, such as RFID tags or any other non-image basedidentifiers associated with each item.

FIG. 1 illustrates two cameras, camera 121 and camera 122. In one ormore embodiments, any number of cameras may be employed to track peopleand items. Cameras may be of any type; for example, cameras may be 2D,3D, or 4D. 3D cameras may be stereo cameras, or they may use othertechnologies such as rangefinders to obtain depth information. One ormore embodiments may use only 2D cameras and may for example determine3D locations by triangulating views of people and items from multiple 2Dcameras. 4D cameras may include any type of camera that can also gatheror calculate depth over time, e.g., 3D video cameras.

Cameras 121 and 122 observe the item storage area 102 and the region orregions of store 101 through which people may move. Different camerasmay observe different item storage areas or different regions of thestore. Cameras may have overlapping views in one or more embodiments.Tracking of a person moving through the store may involve multiplecameras, since in some embodiments no single camera may have a view ofthe entire store.

Camera images are input into processor 130, which analyzes the images totrack people and items in the store. Processor 130 may be any type ortypes of computer or other device. In one or more embodiments, processor130 may be a network of multiple processors. When processor 130 is anetwork of processors, different processors in the network may analyzeimages from different cameras. Processors in the network may shareinformation and cooperate to analyze images in any desired manner. Theprocessor or processors 130 may be onsite in the store 101, or offsite,or a combination of onsite and offsite processing may be employed.Cameras 121 and 122 may transfer data to the processor over any type ortypes of network or link, including wired or wireless connections.Processor 130 includes or couples with memory, RAM or disk and may beutilized as a non-transitory data storage computer-readable media thatembodiments of the invention may utilize or otherwise include toimplement all functionality detailed herein.

Processor or processors 130 may also access or receive a 3D model 131 ofthe store and may use this 3D model to analyze camera images. The model131 may for example describe the store dimensions, the locations of itemstorage areas and items and the location and orientation of the cameras.The model may for example include the floorplan of the store, as well asmodels of item storage areas such as shelves and displays. This modelmay for example be derived from a store's planogram, which details thelocation of all shelving units, their height, as well as which items areplaced on them. Planograms are common in retail spaces, so should beavailable for most stores. Using this planogram, measurements may forexample be converted into a 3D model using a 3D CAD package.

If no planogram is available, other techniques may be used to obtain theitem storage locations. One illustrative technique is to measure thelocations, shapes and sizes of all shelves and displays within thestore. These measurements can then be directly converted into aplanogram or 3D CAD model. A second illustrative technique involvestaking a series of images of all surfaces within the store including thewalls, floors and ceilings. Enough images may be taken so that eachsurface can be seen in at least two images. Images can be either stillimages or video frames. Using these images, standard 3D reconstructiontechniques can be used to reconstruct a complete model of the store in3D.

In one or more embodiments, a 3D model 131 used for analyzing cameraimages may describe only a portion of a site, or it may describe onlyselected features of the site. For example, it may describe only thelocation and orientation of one or more cameras in the site; thisinformation may be obtained for example from extrinsic calibration ofcamera parameters. A basic, minimal 3D model may contain only thiscamera information. In one or more embodiments, geometry describing allor part of a store may be added to the 3D model for certainapplications, such as associating the location of people in the storewith specific product storage areas. A 3D model may also be used todetermine occlusions, which may affect the analysis of camera images.For example, a 3D model may determine that a person is behind a cabinetand is therefore occluded by the cabinet from the viewpoint of a camera;tracking of the person or extraction of the person's appearance maytherefore not use images from that camera while the person is occluded.

Cameras 121 and 122 (and other cameras in store 101 if available) mayobserve item storage areas such as area 102, as well as areas of thestore where people enter, leave and circulate. By analyzing cameraimages over time, the processor 130 may track people as they movethrough the store. For example, person 103 is observed at time 141standing near item storage area 102 and at a later time 142 after he hasmoved away from the item storage area. Using possibly multiple camerasto triangulate the person's position and the 3D store model 131, theprocessor 130 may detect that person 103 is close enough to item storagearea 102 at time 141 to move items on the shelf. By comparing images ofstorage area 102 at times 141 and 142, the system may detect that item111 has been moved and may attribute this motion to person 103 sincethat person was proximal to the item in the time range between 141 and142. Therefore, the system derives information 150 that the person 103took item 111 from shelf 102. This information may be used for examplefor automated checkout, for shoplifting detection, for analytics ofshopper behavior or store organization, or for any other purposes. Inthis illustrative example, person 103 is given an anonymous tag 151 fortracking purposes. This tag may or may not be cross referenced to otherinformation such as for example a shopper's credit card information; inone or more embodiments the tag may be completely anonymous and may beused only to track a person through the store. This enables associationof a person with products without require identification of who thatparticular user is. This is important in locales where people typicallywear masks when sick, or other garments which cover the face forexample. Also shown is electronic device 119 that generally includes adisplay that the system may utilize to show the person's list of items,i.e., shopping cart list and with which the person may pay for the itemsfor example.

In one or more embodiments, camera images may be supplemented with othersensor data to determine which products are removed or the quantity of aproduct that is taken or dispensed. For example, a product shelf such asshelf 102 may have weight sensors or motion sensors that assist indetecting that products are taken, moved, or replaced on the shelf. Oneor more embodiments may receive and process data indicating the quantityof a product that is taken or dispensed, and may attribute this quantityto a person, for example to charge this quantity to the person'saccount. For example, a dispenser of a liquid such as a beverage mayhave a flow sensor that measures the amount of liquid dispensed; datafrom the flow sensor may be transmitted to the system to attribute thisamount to a person proximal to the dispenser at the time of dispensing.A person may also press a button or provide other input to determinewhat products or quantities should be dispensed; data from the button orother input device may be transmitted to the system to determine whatitems and quantities to attribute to a person.

FIG. 2 continues the example of FIG. 1 to show an automated checkout. Inone or more embodiments, processor 130 or another linked system maydetect that a person 103 is leaving a store or is entering an automatedcheckout area. For example, a camera or cameras such as camera 202 maytrack person 103 as he or she exits the store. If the system 130 hasdetermined that person 103 has an item, such as item 111 and if thesystem is configured to support automated checkout, then it may transmita message 203 or otherwise interface with a checkout system such as apoint of sale system 210. This message may for example trigger anautomated charge 211 for the item (or items) believed to be taken byperson 103, which may for example be sent to financial institution orsystem 212. In one or more embodiments a message 213 may also bedisplayed or otherwise transmitted to person 103 confirming the charge,e.g., on the person's electronic device 119 shown in FIG. 1. The message213 may for example be displayed on a display visible to the personexiting or in the checkout area, or it may be transmitted for examplevia a text message or email to the person, for example to a computer ormobile device 119 (see FIG. 1) associated with the user. In one or moreembodiments the message 213 may be translated to a spoken message. Thefully automated charge 211 may for example require that the identity ofperson 103 be associated with financial information, such as a creditcard for example. One or more embodiments may support other forms ofcheckout that may for example not require a human cashier but may askperson 103 to provide a form of payment upon checkout or exit. Apotential benefit of an automated checkout system such as that shown inFIG. 2 is that the labor required for the store may be eliminated orgreatly reduced. In one or more embodiments, the list of items that thestore believes the user has taken may be sent to a mobile deviceassociated with the user for the user's review or approval.

As illustrated in FIG. 1, in one or more embodiments analysis of asequence of two or more camera images may be used to determine that aperson in a store has interacted with an item in an item storage area.FIG. 3 shows an illustrative embodiment that uses an artificial neuralnetwork 300 to identify an item that has been moved from a pair ofimages, e.g., an image 301 obtained prior to the move of the item and animage 302 obtained after the move of the item. One or more embodimentsmay analyze any number of images, including but not limited to twoimages. These images 301 and 302 may be fed as inputs into input layer311 of a neural network 300, for example. (Each color channel of eachpixel of each image may for example be set as the value of an inputneuron in input layer 311 of the neural network.) The neural network 300may then have any number of additional layers 312, connected andorganized in any desired fashion. For example, without limitation, theneural network may employ any number of fully connected layers,convolutional layers, recurrent layers, or any other type of neurons orconnections. In one or more embodiments the neural network 300 may be aSiamese neural network organized to compare the two images 301 and 302.In one or more embodiments, neural network 300 may be a generativeadversarial network, or any other type of network that performsinput-output mapping.

The output layer 313 of the neural network 300 may for example containprobabilities that each item was moved. One or more embodiments mayselect the item with the highest probability, in this case output neuron313 and associate movement of this item with the person near the itemstorage area at the time of the movement of the item. In one or moreembodiments there may be an output indicating no item was moved.

The neural network 300 of FIG. 3 also has outputs classifying the typeof movement of the item. In this illustrative example there are threetypes of motions: a take action 321, which indicates for example thatthe item appeared in image 301 but not in image 302; a put action 322,which indicates for example that the item appears in image 302 but notin image 301; and a move action 323, which indicates for example thatthe item appears in both images but in a different location. Theseactions are illustrative; one or more embodiments may classify movementor rearrangement of items into any desired classes and may for exampleassign a probability to each class. In one or more embodiments, separateneural networks may be used to determine the item probabilities and theaction class probabilities. In the example of FIG. 3, the take class 321has the highest calculated probability, indicating that the system mostlikely detects that the person near the image storage area has taken theitem away from the storage area.

The neural network analysis as indicated in FIG. 3 to determine whichitem or items have been moved and the types of movement actionsperformed is an illustrative technique for image analysis that may beused in one or more embodiments. One or more embodiments may use anydesired technique or algorithm to analyze images to determine items thathave moved and the actions that have been performed. For example, one ormore embodiments may perform simple frame differences on images 301 and302 to identify movement of items. One or more embodiments maypreprocess images 301 and 302 in any desired manner prior to feedingthem to a neural network or other analysis system. For example, withoutlimitation, preprocessing may align images, remove shadows, equalizelighting, correct color differences, or perform any other modifications.Images may be processed with any classical image processing algorithmssuch as color space transformation, edge detection, smoothing orsharpening, application of morphological operators, or convolution withfilters.

One or more embodiments may use machine learning techniques to deriveclassification algorithms such as the neural network algorithm appliedin FIG. 3. FIG. 4 shows an illustrative process for learning the weightsof the neural network 300 of FIG. 3. A training set 401 of examples maybe collected or generated and used to train network 300. Trainingexamples such as examples 402 and 403 may for example include before andafter images of an item storage area and output labels 412 and 413 thatindicate the item moved and the type of action applied to the item.These examples may be constructed manually, or in one or moreembodiments there may be an automated training process that capturesimages and then uses checkout data that associates items with persons tobuild training examples. FIG. 4A shows an example of augmenting thetraining data with examples that correct misclassifications by thesystem. In this example, the store checkout is not fully automated;instead, a cashier 451 assists the customer with checkout. The system130 has analyzed camera images and has sent message 452 to the cashier'spoint of sale system 453. The message contains the system'sdetermination of the item that the customer has removed from the itemstorage area 102. However, in this case the system has made an error.Cashier 451 notices the error and enters a correction into the point ofsale system with the correct item. The corrected item and the imagesfrom the camera may then be transmitted as a new training example 454that may be used to retrain neural network 300. In time, the cashier maybe eliminated when the error rate converges to an acceptable predefinedlevel. In one or more embodiments, the user may show the erroneous itemto the neural network via a camera and train the system without cashier451. In other embodiments, cashier 451 may be remote and accessed viaany communication method including video or image and audio-basedsystems.

In one or more embodiments, people in the store may be tracked as theymove through the store. Since multiple people may be moving in the storesimultaneously, it may be beneficial to distinguish between personsusing image analysis, so that people can be correctly tracked. FIG. 5shows an illustrative method that may be used to distinguish amongdifferent persons. As a new person 501 enters a store or enters aspecified area or areas of the store at time 510, images of the personfrom cameras such as cameras 511, 512 and 513 may be analyzed todetermine certain characteristics 531 of the person's appearance thatcan be used to distinguish that person from other people in the store.These distinguishing characteristics may include for example, withoutlimitation: the size or shape of certain body parts; the color, shape,style, or size of the person's hair; distances between selectedlandmarks on the person's body or clothing; the color, texture,materials, style, size, or type of the person's clothing, jewelry,accessories, or possessions; the type of gait the person uses whenwalking or moving; the speed or motion the person makes with any part oftheir body such as hands, arms, legs, or head; and gestures the personmakes. One or more embodiments may use high resolution camera images toobserve biometric information such as a person's fingerprints orhandprints, retina, or other features.

In the example shown in FIG. 5, at time 520 a person 502 enters thestore and is detected to be a new person. New distinguishingcharacteristics 532 are measured and observed for this person. Theoriginal person 501 has been tracked and is now observed to be at a newlocation 533. The observations of the person at location 533 are matchedto the distinguishing characteristics 531 to identify the person asperson 501.

In the example of FIG. 5, although distinguishing characteristics areidentified for persons 501 and 502, the identities of these individualsremain anonymous. Tags 541 and 542 are assigned to these individuals forinternal tracking purposes, but the persons' actual identities are notknown. This anonymous tracking may be beneficial in environments whereindividuals do not want their identities to be known to the autonomousstore system. Moreover, sensitive identifying information, such as forexample images of a person's face, need not be used for tracking; one ormore embodiments may track people based on other less sensitiveinformation such as the distinguishing characteristics 531 and 532. Aspreviously described, in some areas, people wear masks when sick orotherwise wear face garments, making identification based on a user'sface impossible.

The distinguishing characteristics 531 and 532 of persons 501 and 502may or may not be saved over time to recognize return visitors to thestore. In some situations, a store may want to track return visitors.For example, shopper behavior may be tracked over multiple visits if thedistinguishing characteristics are saved and retrieved for each visitor.Saving this information may also be useful to identify shoplifters whohave previously stolen from the store, so that the store personnel orauthorities can be alerted when a shoplifter or potential shoplifterreturns to the store. In other situations, a store may want to deletedistinguishing information when a shopper leaves the store, for exampleif there are potential concern that the store may be collectinginformation that the shopper's do not want saved over time.

In one or more embodiments, the system may calculate a 3D field ofinfluence volume around a person as it tracks the person's movementthrough the store. This 3D field of influence volume may for exampleindicate a region in which the person can potentially touch or moveitems. A detection of an item that has moved may for example beassociated with a person being tracked only if the 3D field of influencevolume for that person is near the item at the time of the item'smovement.

Various methods may be used to calculate a 3D field of influence volumearound a person. FIGS. 6A through 6E illustrate a method that may beused in one or more embodiments. (These figures illustrate theconstruction of a field of influence volume using 2D figures, for easeof illustration, but the method may be applied in three dimensions tobuild a 3D volume around the person.) Based on an image or images 601 ofa person, image analysis may be used to identify landmarks on theperson's body. For example, landmark 602 may be the left elbow of theperson. FIG. 6B illustrates an analysis process that identifies 18different landmarks on the person's body. One or more embodiments mayidentify any number of landmarks on a body, at any desired level ofdetail. Landmarks may be connected in a skeleton in order to track themovement of the person's joints. Once landmark locations are identifiedin the 3D space associated with the store, one method for constructing a3D field of influence volume is to calculate a sphere around eachlandmark with a radius of a specified threshold distance. For example,one or more embodiments may use a threshold distance of 25 cm offsetfrom each landmark. FIG. 6C shows sphere 603 with radius 604 aroundlandmark 602. These spheres may be constructed around each landmark, asillustrated in FIG. 6D. The 3D field of influence volume may then becalculated as the union of these spheres around the landmarks, asillustrated with 3D field of influence volume 605 in FIG. 6E.

Another method of calculating a 3D field of influence volume around aperson is to calculate a probability distribution for the location ofeach landmark and to define the 3D field of influence volume around alandmark as a region in space that contains a specified threshold amountof probability from this probability distribution. This method isillustrated in FIGS. 7A and 7B. Images of a person are used to calculatelandmark positions 701, as described with respect to FIG. 6B. As theperson is tracked through the store, uncertainty in the tracking processresults in a probability distribution for the 3D location of eachlandmark. This probability distribution may be calculated and trackedusing various methods, including a particle filter as described belowwith respect to FIG. 8. For example, for the right elbow landmark 702 inFIG. 7A, a probability density 703 may be calculated for the position ofthe landmark. (This density is shown in FIG. 7A as a 2D figure for easeof illustration, but in tracking it will generally be a 3D spatialprobability distribution.) A volume may be determined that contains aspecified threshold probability amount of this probability density foreach landmark. For example, the volume enclosed by surface may enclose95% (or any other desired amount) of the probability distribution 703.The 3D field of influence volume around a person may then be calculatedas the union of these volumes 704 around each landmark, as illustratedin FIG. 7B. The shape and size of the volumes around each landmark maydiffer, reflecting differences in the uncertainties for tracking thedifferent landmarks.

FIG. 8 illustrates a technique that may be used in one or moreembodiments to track a person over time as he or she moves through astore. The state of a person at any point in time may for example berepresented as a probability distribution of certain state variablessuch as the position and velocity (in three dimensions) of specificlandmarks on the person's body. One approach to representing thisprobability distribution is to use a particle filter, where a set ofparticles is propagated over time to represent weighted samples from thedistribution. In the example of FIG. 8, two particles 802 and 803 areshown for illustration; in practice the probability distribution at anypoint in time may be represented by hundreds or thousands of particles.To propagate state 801 to a subsequent point in time, one or moreembodiments may employ an iterative prediction/correction loop. State801 is first propagated through a prediction step 811, which may forexample use a physics model to estimate for each particle what the nextstate of the particle is. The physics model may include for example,without limitation, constraints on the relative location of landmarks(for example, a constraint that the distance between the left foot andthe left knee is fixed), maximum velocities or accelerations at whichbody parts can move and constraints from barriers in the store, such asfloors, walls, fixtures, or other persons. These physics modelcomponents are illustrative; one or more embodiments may use any type ofphysics model or other model to propagate tracking state from one timeperiod to another. The predict step 811 may also reflect uncertaintiesin movements, so that the spread of the probability distribution mayincrease over time in each predict step, for example. The particlesafter the prediction step 811 are then propagated through a correctionstep 812, which incorporates information obtained from measurements incamera images, as well as other information if available. The correctionstep uses camera images such as images 821, 822, 823 and information onthe camera projections of each camera as well as other cameracalibration data if available. As illustrated in images 821, 822 and823, camera images may provide only partial information due to occlusionof the person or to images that capture only a portion of the person'sbody. The information that is available is used to correct thepredictions, which may for example reduce the uncertainty in theprobability distribution of the person's state. Thisprediction/correction loop may be repeated at any desired interval totrack the person through the store.

By tracking a person as he or she moves through the store, one or moreembodiments of the system may generate a 3D trajectory of the personthrough the store. This 3D trajectory may be combined with informationon movement of items in item storage areas to associate people with theitems they interact with. If the person's trajectory is proximal to theitem at a time when the item is moved, then the movement of the item maybe attributed to that person, for example. FIG. 9 illustrates thisprocess. For ease of illustration, the person's trajectory and the itemposition are shown in two dimensions; one or more embodiments mayperform a similar analysis in three dimensions using the 3D model of thestore, for example. A trajectory 901 of a person is tracked over time,using a tracking process such as the one illustrated in FIG. 8, forexample. For each person, a 3D field of influence volume 902 may becalculated at each point in time, based for example on the location orprobability distribution of landmarks on the person's body. (Again, forease of illustration the field of influence volume shown in FIG. 9 is inthe two dimension, although in implementation this volume may be threedimensional.) The system calculates the trajectory of the 3D influencevolume through the store. Using camera image analysis such as theanalysis illustrated in FIG. 3, motion 903 of an item is detected at alocation 904. Since there may be multiple people tracked in a store, themotion may be attributed to the person whose field of influence volumewas at or near this location at the time of motion. Trajectory 901 showsthat the field of influence volume of this tracked person intersectedthe location of the moved item during a time interval proximal in timeto this motion; hence the item movement may be attributed to thisperson.

In one or more embodiments the system may optimize the analysisdescribed above with respect to FIG. 9 by looking for item movementsonly in item storage areas that intersect a person's 3D field ofinfluence volume. FIG. 10 illustrates this process. At a point in time141 or over a time interval, the tracked 3D field of influence volume1001 of person 103 is calculated to be near item storage area 102. Thesystem therefore calculates an intersection 1011 of the item storagearea 102 and the 3D field of influence volume 1001 around person 1032and locates camera images that contain views of this region, such asimage 1011. At a subsequent time 142, for example when person 103 isdetermined to have moved away from item storage area 102, an image 1012(or multiple such images) is obtained of the same intersected region.These two images are then fed as inputs to neural network 300, which mayfor example detect whether any item was moved, which item was moved (ifany) and the type of action that was performed. The detected item motionis attributed to person 103 because this is the person whose field ofinfluence volume intersected the item storage area at the time ofmotion. By applying the classification analysis of neural network 300only to images that represent intersections of person's field ofinfluence volume with item storage areas, processing resources may beused efficiently and focused only on item movement that may beattributed to a tracked person.

FIGS. 11 through 15 show screenshots of an embodiment of the system inoperation in a typical store environment. FIG. 11 shows three cameraimages 1101, 1102 and 1103 taken of shoppers moving through the store.In image 1101, two shoppers 1111 and 1112 have been identified andtracked. Image 1101 shows landmarks identified on each shopper that areused for tracking and for generating a 3D field of influence volumearound each shopper. Distances between landmarks and other features suchas clothing may be used to distinguish between shoppers 1111 and 1112and to track them individually as they move through the store. Images1102 and 1103 show views of shopper 1111 as he approaches item storagearea 1113 and picks up an item 114 from the item storage area. Images1121 and 1123 show close up views from images 1101 and 1103,respectively, of item storage area 1113 before and after shopper 1111picks up the item.

FIG. 12 continues the example shown in FIG. 11 to show how images 1121and 1123 of the item storage area are fed as inputs into a neuralnetwork 1201 to determine what item, if any, has been moved by shopper1111. The network assigns the highest probability to item 1202. FIG. 13shows how the system attributes motion of this item 1202 to shopper 1111and assigns an action 1301 to indicate that the shopper picked up theitem. This action 1301 may also be detected by neural network 1201, orby a similar neural network. Similarly, the system has detected thatitem 1303 has been moved by shopper 1112 and it assigns action 1302 tothis item movement.

FIG. 13 also illustrates that the system has detected a “look at” action1304 by shopper 1111 with respect to item 1202 that the shopper pickedup. In one or more embodiments, the system may detect that a person islooking at an item by tracking the eyes of the person (as landmarks, forexample) and by projecting a field of view from the eyes towards items.If an item is within the field of view of the eyes, then the person maybe identified as looking at the item. For example, in FIG. 13 the fieldof view projected from the eyes landmarks of shopper 1111 is region 1305and the system may recognize that item 1202 is within this region. Oneor more embodiments may detect that a person is looking at an itemwhether or not that item is moved by the person; for example, a personmay look at an item in an item storage area while browsing and maysubsequently choose not to touch the item.

In one or more embodiments, other head landmarks instead of or inaddition to the eyes may be used to compute head orientation relative tothe store reference frame to determine what a person is looking at. Headorientation may be computed for example via 3D triangulated headlandmarks. One or more embodiments may estimate head orientation from 2Dlandmarks using for example a neural network that is trained to estimategaze in 3D from 2D landmarks.

FIG. 14 shows a screenshot 1400 of the system creating a 3D field ofinfluence volume around a shopper. The surface of the 3D field ofinfluence volume 1401 is represented in this image overlay as a set ofdots on the surface. The surface 1401 may be generated as an offset fromlandmarks identified on the person, such as landmark 1402 for theperson's right foot for example. Screenshot 1410 shows the location ofthe landmarks associated with the person in the 3D model of the store.

FIG. 15 continues the example of FIG. 14 to show tracking of the personand his 3D field of influence volume as he moves through the store incamera images 1501 and 1502 and generation of a trajectory of theperson's landmarks in the 3D model of the store in screenshots 1511 and1512.

In one or more embodiments, the system may use camera calibration datato transform images obtained from cameras in the store. Calibration datamay include for example, without limitation, intrinsic cameraparameters, extrinsic camera parameters, temporal calibration data toalign camera image feeds to a common time scale and color calibrationdata to align camera images to a common color scale. FIG. 16 illustratesthe process of using camera calibration data to transform images. Asequence of raw images 1601 is obtained from camera 121 in the store. Acorrection 1602 for intrinsic camera parameters is applied to these rawimages, resulting in corrected sequence 1603. Intrinsic cameraparameters may include for example the focal length of the camera, theshape and orientation of the imaging sensor, or lens distortioncharacteristics. Corrected images 1603 are then transformed in step 1604to map the images to the 3D store model, using extrinsic cameraparameters that describe the camera projection transformation based onthe location and orientation of the camera in the store. The resultingtransformed images 1605 are projections aligned with respect to acoordinate system 1606 of the store. These transformed images 1605 maythen be shifted in time to account for possible time offsets amongdifferent cameras in the store. This shifting 1607 synchronizes theframes from the different cameras in the store to a common time scale.In the last transformation 1609, the color of pixels in the timecorrected frames 1608 may be modified to map colors to a common colorspace across the cameras in the store, resulting in final calibratedframes 1610. Colors may vary across cameras because of differences incamera hardware or firmware, or because of lighting conditions that varyacross the store; color correction 1609 ensures that all cameras viewthe same object as having the same color, regardless of where the objectis in the store. This mapping to a common color space may for examplefacilitate the tracking of a person or an item selected by a person asthe person or item moves from the field of view of one camera to anothercamera, since tracking may rely in part on the color of the person oritem.

The camera calibration data illustrated in FIG. 16 may be obtained fromany desired source. One or more embodiments may also include systems,processes, or methods to generate any or all of this camera calibrationdata. FIG. 17 illustrates an embodiment that generates cameracalibration data 1701, including for example any or all of intrinsiccamera parameters, extrinsic camera parameter, time offsets for temporalsynchronization and color mapping from each camera to a common colorspace. Store 1702 contains for this example three cameras, 1703, 1704and 1705. Images from these cameras are captured during calibrationprocedures and are analyzed by camera calibration system 1710. Thissystem may be the same as or different from the system or systems usedto track persons and items during store operations. Calibration system1710 may include or communicate with one or more processors. Forcalibration of intrinsic camera parameters, standard camera calibrationgrids for example may be placed in the store 1702. For calibration ofextrinsic camera parameters, markers of a known size and shape may forexample be placed in known locations in the store, so that the positionand orientation of cameras 1703, 1704 and 1705 may be derived from theimages of the markers. Alternatively, an iterative procedure may be usedthat simultaneously solves for marker positions and for camera positionsand orientations.

A temporal calibration procedure that may be used in one or moreembodiments is to place a source of light 1705 in the store and to pulsea flash of light from the source 1705. The time that each cameraobserves the flash may be used to derive the time offset of each camerafrom a common time scale. The light flashed from source 1705 may bevisible, infrared, or of any desired wavelength or wavelengths. If allcameras cannot observe a single source, then either multiplesynchronized light sources may be used, or cameras may be iterativelysynchronized in overlapping groups to a common time scale.

A color calibration procedure that may be used in one or moreembodiments is to place one or more markers of known colors into thestore and to generate color mappings from each camera into a known colorspace based on the images of these markers observed by the cameras. Forexample, color markers 1721, 1722 and 1723 may be placed in the store;each marker may for example have a grid of standard color squares. Inone or more embodiments the color markers may also be used forcalibration of extrinsic parameters; for example, they may be placed inknown locations as shown in FIG. 17. In one or more embodiments items inthe store may be used for color calibration if for example they are of aknown color.

Based on the observed colors of the markers 1721, 1722 and 1723 in aspecific camera, a mapping may be derived to transform the observedcolors of the camera to a standard color space. This mapping may belinear or nonlinear. The mapping may be derived for example using aregression or using any desired functional approximation methodology.

The observed color of any object in the store, even in a camera that iscolor calibrated to a standard color space, depends on the lighting atthe location of the object in the store. For example, in store 1702 anobject near light 1731 or near window 1732 may appear brighter thanobjects at other locations in the store. To correct for the effect oflighting variations on color, one or more embodiments may create and/oruse a map of the luminance or other lighting characteristics across thestore. This luminance map may be generated based on observations oflighting intensity from cameras or from light sensors, on models of thestore lighting, or on a combination thereof. In the example of FIG. 17,illustrative luminance map 1741 may be generated during or prior tocamera calibration and it may be used in mapping camera colors to astandard color space. Since lighting conditions may change at differenttimes of day, one or more embodiments may generate different luminancemaps for different times or time periods. For example, luminance map1742 may be used for nighttime operation, when light from window 1732 isdiminished but store light 1731 continues to operate.

In one or more embodiments, filters may be added to light sources or tocameras, or both, to improve tracking and detection. For example, pointlights may cause glare in camera images from shiny products. Polarizingfilters on light may reduce this glare, since polarized light generatesless glare. Polarizing filters on light sources may be combined withpolarizers on cameras to further reduce glare.

In addition to or instead of using different luminance maps at differenttimes to account for changes in lighting conditions, one or moreembodiments may recalibrate cameras as needed to account for the effectsof changing lighting conditions on camera color maps. For example, atimer 1751 may trigger camera calibration procedure 1710, so that forexample camera colors are recalibrated at different times of day.Alternatively, or in addition, light sensors 1752 located in store 1702may trigger camera calibration procedure 1710 when the sensor or sensorsdetect that lighting conditions have changed or may have changed.Embodiments of the system may also sub-map calibration to specific areasof images, for example if window 1732 allows sunlight in to a portion ofthe store. In other words, the calibration data may also be based onarea and time to provide even more accurate results.

In one or more embodiments, camera placement optimization may beutilized in the system. For example, in a 2D camera scenario, one methodthat can be utilized is to assign a cost function to camera positions tooptimize the placement and number of cameras for a particular store. Inone embodiment, assigning a penalty of 1000 to any item that is onlyfound in one image from the cameras results in a large penalty for anyitem only viewable by one camera. Assigning a penalty of 1 to the numberof cameras results in a slight penalty for additional cameras requiredfor the store. By penalizing camera placements that do not produce atleast two images or a stereoscopic image of each item, then the numberof items for which 3D locations cannot be obtained is heavily penalizedso that the final camera placement is under a predefined cost. One ormore embodiments thus converge on a set of camera placements where twodifferent viewpoints to all items is eliminated given enough cameras. Byplacing a cost function on the number of cameras, the iterative solutionaccording to this embodiment thus is employed to find at least onesolution with a minimal number of cameras for the store. As shown in theupper row of FIG. 18, the items on the left side of the store only haveone camera, the middle camera pointing towards them. Thus, those itemsin the upper right table incur a penalty of 1000 each. Since there are 3cameras in this iteration, the total cost is 2003. In the nextiteration, a camera is added as shown in the middle row of the figure.Since all items can now be seen by at least two cameras, the cost dropsto zero for items, while another camera has been added so that the totalcost is 4. In the bottom row as shown for this iteration, a camera isremoved, for example by determining that certain items are viewed bymore than 2 cameras as shown in the middle column of the middle rowtable, showing 3 views for 4 items. After removing the far-left camerain the bottom row store, the cost decreases by 1, thus the total cost is3. Any number of camera positions, orientations and types may beutilized in embodiments of the system. One or more embodiments of thesystem may optimize the number of cameras by using existing securitycameras in a store and by moving those cameras if needed or augmentingthe number of cameras for the store to leverage existing videoinfrastructure in a store, for example in accordance with the cameracalibration previously described. Any other method of placing andorienting cameras, for example equal spacing and a predefined angle toset an initial scenario may be utilized.

In one or more embodiments, one or more of the techniques describedabove to track people and their interactions with an environment may beapplied to extend an authorization obtained by a person at one point intime and space to another point in time or space. For example, anauthorization may be obtained by a person at an entry point to an areaor a check point in the area and at an initial point in time. Theauthorization may authorize the person to perform one or more actions,such as for example to enter a secure environment such as a lockedbuilding, or to charge purchases to an account associated with theperson. The system may then track this person to a second location at asubsequent point in time and may associate the previously obtainedauthorization with that person at the second location and at thesubsequent point in time. This extension of an authorization across timeand space may simplify the interaction of the person with theenvironment. For example, a person may need to or choose to present acredential (such as a payment card) at the entry point to obtain anauthorization to perform purchases; because the system may track thatperson afterwards, this credential may not need to be presented again touse the previously obtained authorization. This extension ofauthorization may for example be useful in automated stores inconjunction with the techniques described above to determine which itemsa person interacts with or takes within the store; a person might forexample present a card at a store entrance or at a payment kiosk or cardreader associated with the store and then simply take items as desiredand be charged for them automatically upon leaving the store, withoutperforming any explicit checkout.

FIG. 19 shows an illustrative embodiment that enables authorizationextension using tracking via analysis of camera images. This figure andseveral subsequent figures illustrate one or more aspects ofauthorization extension using a gas station example. This example isillustrative; one or more embodiments may enable authorization extensionat any type of site or area. For example, without limitation,authorization extension may be applied to or integrated into all of orany portion of a building, a multi-building complex, a store, arestaurant, a hotel, a school, a campus, a mall, a parking lot, anindoor or outdoor market, a residential building or complex, a room, astadium, a field, an arena, a recreational area, a park, a playground, amuseum, or a gallery. It may be applied or integrated into anyenvironment where an authorization obtained at one time and place may beextended to a different time or different place. It may be applied toextend any type of authorization.

In the example shown in FIG. 19, a person 1901 arrives at a gas stationand goes to gas pump 1902. To obtain gas (or potentially to authorizeother actions without obtaining gas), person 1901 presents a credential1904, such as for example a credit or debit card, into credential reader1905 on or near the pump 1902. The credential reader 1905 transmits amessage 1906 to a bank or clearinghouse 212 to obtain an authorization1907, which allows user 1901 to pump gas from pump 1902.

In one or more embodiments, a person may present any type of credentialto any type of credential reader to obtain an authorization. Forexample, without limitation, a credential may be a credit card, a debitcard, a bank card, an RFID tag, a mobile payment device, a mobile walletdevice, a mobile phone, a smart phone, a smart watch, smart glasses orgoggles, a key fob, an identity card, a driver's license, a passport, apassword, a PIN, a code, a phone number, or a biometric identifier. Acredential may be integrated into or attached to any device carried by aperson, such as a mobile phone, smart phone, smart watch, smart glasses,key fob, smart goggles, tablet, or computer. A credential may be worn bya person or integrated into an item of clothing or an accessory worn bya person. A credential may be passive or active. A credential may or maynot be linked to a payment mechanism or an account. In one or moreembodiments a credential may be a password, PIN, code, phone number, orother data typed or spoken or otherwise entered by a person into acredential reader. A credential reader may be any device or combinationof devices that can read or accept a presented credential. A credentialreader may or may not be linked to a remote authorization system likebank 212. In one or more embodiments a credential reader may have localinformation to authorize a user based on a presented credential withoutcommunicating with other systems. A credential reader may read,recognize, accept, authenticate, or otherwise process a credential usingany type of technology. For example, without limitation, a credentialreader may have a magnetic stripe reader, a chip card reader, an RFIDtag reader, an optical reader or scanner, a biometric reader such as afingerprint scanner, a near field communication receiver, a Bluetoothreceiver, a Wi-Fi receiver, a keyboard or touchscreen for typed input,or a microphone for audio input. A credential reader may receivesignals, transmit signals, or both.

In one or more embodiments, an authorization obtained by a person may beassociated with any action or actions the person is authorized toperform. These actions may include, but are not limited to, financialtransactions such as purchases. Actions that may be authorized mayinclude for example, without limitation, entry to or exit from abuilding, room, or area; purchasing or renting of items, products, orservices; use of items, products, or services; or access to controlledinformation or materials.

In one or more embodiments, a credential reader need not be integratedinto a gas pump or into any other device. It may be standalone, attachedto or integrated into any device, or distributed across an area. Acredential reader may be located in any location in an area, includingfor example, without limitation, at an entrance, exit, check-in point,checkpoint, control point, gate, door, or other barrier. In one or moreembodiments, several credential readers may be located in an area;multiple credential readers may be used simultaneously by differentpersons.

The embodiment illustrated in FIG. 19 extends the authorization forpumping gas obtained by person 1901 to authorize one or more otheractions by this person, without requiring the person to re-presentcredential 1904. In this illustrative example, the gas station has anassociated convenience store 1903 where customers can purchase products.The authorization extension embodiment may enable the convenience storeto be automated, for example without staff. Because the store 1903 maybe unmanned, the door 1908 to the store may be locked, for example witha controllable lock 1909, thereby preventing entry to the store byunauthorized persons. The embodiment described below extends theauthorization of person 1901 obtained by presenting credential 1904 atthe pump 1902 to enable the person 1901 to enter store 1903 throughlocked door 1908.

One or more embodiments may enable authorization extension to allow auser to enter a secured environment of any kind, including but notlimited to a store such as convenience store 1903 in FIG. 19. Thesecured environment may have an entry that is secured by a barrier, suchas for example, without limitation, a door, gate, fence, grate, orwindow. The barrier may not be a physical device preventing entry; itmay be for example an alarm that must be disabled to enter the securedenvironment without sounding the alarm. In one or more embodiments thebarrier may be controllable by the system so that for example commandsmay be sent to the barrier to allow (or to disallow) entry. For example,without limitation, an electronically controlled lock to a door or gatemay provide a controllable barrier to entry.

In FIG. 19, authorization extension may be enabled by tracking theperson 1901 from the point of authorization to the point of entry to theconvenience store 1903. Tracking may be performed using one or morecameras in the area. In the gas station example of FIG. 19, cameras1911, 1912 and 1913 are installed in or around the area of the gasstation. Images from the cameras are transmitted to processor 130, whichprocesses these images to recognize people and to track them over a timeperiod as they move through the gas station area. Processor 130 may alsoaccess and use a 3D model 1914. The 3D model 1914 may for exampledescribe the location and orientation of one or more cameras in thesite; this data may be obtained for example from extrinsic cameracalibration. In one or more embodiments, the 3D model 1914 may alsodescribe the location of one or more objects or zones in the site, suchas the pump and the convenience store in the gasoline station site ofFIG. 19. The 3D model 1914 need not be a complete model of the entiresite; a minimal model may for example contain only enough information onone or more cameras to support tracking of persons in locations orregions of the site that are relevant to the application.

Recognition, tracking and calculation of a trajectory associated with aperson may be performed for example as described above with respect toFIGS. 1 through 10 and as illustrated in FIG. 15. Processor 130 maycalculate a trajectory 1920 for person 1901, beginning for example at apoint 1921 at time 1922 when the person enters the area of the gasstation or is first observed by one or more cameras. The trajectory maybe continuously updated as the person moves through the area. Thestarting point 1921 may or may not coincide with the point 1923 at whichthe person presents credential 1904. On beginning tracking of a person,the system may for example associate a tag 1931 with the person 1901 andwith the trajectory 1920 that is calculated over a period of time forthis person as the person is tracked through the area. This tag 1931 maybe associated with distinguishing characteristics of the person (forexample as described above with respect to FIG. 5). In one or moreembodiments it may be an anonymous tag that is an internal identifierused by processor 130.

The trajectory 1920 calculated by processor 130, which may be updated asthe person 1901 moves through the area, may associate locations withtimes. For example, person 1901 is at location 1921 at time 1922. In oneor more embodiments the locations and the times may be ranges ratherthan specific points in space and time. These ranges may for examplereflect uncertainties or limitations in measurement, or the effects ofdiscrete sampling. For example, if a camera captures images everysecond, then a time associated with a location obtained from one cameraimage may be a time range with a width of two seconds. Sampling andextension of a trajectory with a new point may also occur in response toan event, such as a person entering a zone or triggering a sensor,instead of or in addition to sampling at a fixed frequency. Ranges forlocation may also reflect that a person occupies a volume in space,rather than a single point. This volume may for example be or be relatedto the 3D field of influence volume described above with respect toFIGS. 6A through 7B.

The processor 130 tracks person 1901 to location 1923 at time 1924,where credential reader 1905 is located. In one or more embodimentslocation 1923 may be the same as location 1921 where tracking begins;however, in one or more embodiments the person may be tracked in an areaupon entering the area and may provide a credential at another time,such as upon entering or exiting a store. In one or more embodiments,multiple credential readers may be present; for example, the gas stationin FIG. 19 may have several pay-at-the-pump stations at which customerscan enter credentials. Using analysis of camera images, processor 130may determine which credential reader a person uses to enter acredential, which allows the processor to associate an authorizationwith the person, as described below.

As a result of entering credential 1904 into credential reader 1905, anauthorization 1907 is provided to gas pump 1902. This authorization, orrelated data, may also be transmitted to processor 130. Theauthorization may for example be sent as a message 1910 from the pump orcredential reader, or directly from bank or payment processor (oranother authorization service) 212. Processor 130 may associate thisauthorization with person 1901 by determining that the trajectory 1920of the person is at or near the location of the credential reader 1904at or near the time that the authorization message is received or thetime that the credential is presented to the credential reader 1905. Inembodiments with multiple credential readers in an area, the processor130 may associate a particular authorization with a particular person bydetermining which credential reader that authorization is associatedwith and by correlating the time of that authorization and the locationof that credential reader with the trajectories of one or more people todetermine which person is at or near that credential reader at thattime. In some situations, the person 1901 may wait at the credentialreader 1905 until the authorization is received; therefore processor 130may use either the time that the credential is presented or the timethat the authorization is received to determine which person isassociated with the authorization.

By determining that person 1901 is at or near location 1923 at or neartime 1924, determining that location 1923 is the location of credentialreader 1905 (or within a zone near the credential reader) anddetermining that authorization 1910 is associated with credential reader1905 and is received at or near time 1924 (or is associated withpresentation of a credential at or near time 1924), processor 130 mayassociate the authorization with the trajectory 1920 of person 1901after time 1924. This association 1932 may for example add an extendedtag 1933 to the trajectory that includes authorization information andmay include account or credential information associated with theauthorization. Processor 130 may also associate certain allowed actionswith the authorization; these allowed actions may be specific to theapplication and may also be specific to the particular authorizationobtained for each person or each credential.

Processor 130 then continues to track the trajectory 1920 of person 1901to the location 1925 at time 1926. This location 1925 as at the entry1908 to the convenience store 1903, which is locked by lock 1909.Because in this example the authorization obtained at the pump alsoallows entry into the store, processor 130 transmits command 1934 to thecontrollable lock 1909, which unlocks door 1908 to allow entry to thestore. (Lock 1909 is shown symbolically as a padlock; in practice it maybe integrated into door 1908 or any barrier, along with electroniccontrols to actuate the barrier to allow or deny entry.) The command1934 to unlock the barrier is issued automatically at or near time 1926when person 1901 arrives at the door, because camera images areprocessed to recognize the person, to determine that the person is atthe door at location 1925 and to associate this person with theauthorization obtained previously as a result of presenting thecredential 1904 at previous time 1924.

One or more embodiments may extend authorization obtained at one pointin time to allow entry to any type of secure environment at a subsequentpoint in time. The secure environment may be for example a store orbuilding as in FIG. 19, or a case or similar enclosed container asillustrated in FIG. 20. FIG. 20 illustrates a gas station example thatis similar to the example shown in FIG. 19; however, in FIG. 20,products are available in an enclosed and locked case as opposed to (orin addition to) in a convenience store. For example, a gas station mayhave cases with products for sale next to or near gas pumps, withauthorization to open the cases obtained by extending authorizationobtained at a pump. In the example of FIG. 20, person 1901 inserts acredential into pump 1902 at location 1923 and time 1924, as describedwith respect to FIG. 19. Processor 130 associates the resultingauthorization with the person and with the trajectory 2000 of the personafter time 1924. Person 1901 then walks to case 2001 that containsproducts for sale. The processor tracks the path of the person tolocation 2002 at time 2003, by analyzing images from cameras 1911 and1913 a. It then issues command 2004 to unlock the controllable lock 2005that locks the door of case 2001, thereby opening the door so that theperson can take products.

In one or more embodiments, a trajectory of a person may be tracked andupdated at any desired time intervals. Depending for example on theplacement and availability of cameras in the area, a person may passthrough one or more locations where cameras do not observe the person;therefore, the trajectory may not be updated in these “blind spots”.However, because for example distinguishing characteristics of theperson being tracked may be generated during one or more initialobservations, it may be possible to pick up the track of the personafter he or she leaves these blind spots. For example, in FIG. 20,camera 1911 may provide a good view of location 1924 at the pump andcamera 1913 a may provide a good view of location 2002 at case 2001, butthere may be no views or limited views between these two points.Nevertheless, processor 130 may recognize that person 1901 is the personat location 2002 at time 2003 and is therefore authorized to open thecase 2001, because the distinguishing characteristics viewed by camera1913 a at time 2003 match those viewed by camera 1911 at time 1924.

FIG. 21 continues the example of FIG. 20. Case 2001 is opened whenperson 1901 is at location 2002. The person then reaches into the caseand removes item 2105. Processor 130 analyzes data from cameras or othersensors that detect removal of item 2105 from the case. In the examplein FIG. 21, these sensors include camera 2101, camera 2102 and weightsensor 2103. Cameras 2101 and 2102 may for example be installed insidecase 2001 and positioned and oriented to observe the removal of an itemfrom a shelf. Processor 130 may determine that person 1901 has taken aspecific item using for example techniques described above with respectto FIGS. 3 and 4. In addition, or alternatively, one or more othersensors may detect removal of a product. For example, a weight sensormay be placed under each item in the case to detect when the item isremoved and data from the weight sensor may be transmitted to processor130. Any type or types of sensors may be used to detect or confirm thata user takes an item. Detection of removal of a product, using any typeof sensor, may be combined with tracking of a person using cameras inorder to attribute the taking of a product to a specific user.

In the scenario illustrated in FIG. 21, person 1901 removes product 2105from case 2001. Processor 130 analyzes data from one or more of cameras2102, 2101, 1913 a and sensor 2103, to determine the item that was takenand to associate that item with person 1901 (based for example on the 3Dinfluence volume of the person being located near the item at the timethe item was moved). Because authorization information 1933 is alsoassociated with the person at the time the item is taken, processor 130may transmit message 2111 to charge the account associated with the userfor the item. This charge may be pre-authorized by the person 1901 bypreviously presenting credential 1904 to credential reader 1905.

FIG. 22 extends the example of FIG. 19 to illustrate the person enteringthe convenience store and taking an item. This example is similar insome respects to the previous example of FIG. 21, in that the persontakes an item from within a secure environment (a case in FIG. 21, aconvenience store in FIG. 22) and a charge is issued for the item basedon a previously obtained authorization. This example is also similar tothe example illustrated in FIG. 2, with the addition that anauthorization is obtained by person 1901 at pump 1902, prior to enteringthe convenience store 1903. External cameras 1911, 1912 and 1913 trackperson 1901 to the entrance 1908 and processor 130 unlocks lock 1909 sothat person 1901 may enter the store. Afterwards images from internalcameras such as camera 202 track the person inside the store and theprocessor analyzes these images to determine that the person takes item111 from shelf 102. At exit 201, message 203 a is generated toautomatically charge the account of the person for the item; the messagemay also be sent to a display in the store (or for example on theperson's mobile phone) indicating what item or items are to be charged.In one or more embodiments the person may be able to enter aconfirmation or to make modifications before the charge is transmitted.In one or more embodiments the processor 130 may also transmit an unlockmessage 2201 to unlock the exit door; this barrier at the exit may forexample force unauthorized persons in the store to provide a paymentmechanism prior to exiting.

In a variation of the example of FIG. 22, in one or more embodiments acredential may be presented by a person at entrance 1908 to the store,rather than at a different location such as at pump 1902. For example, acredential reader may be placed within or near the entrance 1908.Alternatively, the entrance to the store may be unlocked and thecredential may be presented at the exit 201. More generally, in one ormore embodiments a credential may be presented and an authorization maybe obtained at any point in time and space and may then be used within astore (or at any other area) to perform one or more actions; theseactions may include, but are not limited to, taking items and havingthem charged automatically to an authorized account. Controllablebarriers, for example on entry or on exit, may or may not be integratedinto the system. For example, the door locks at the store entrance 1908and at the exit 201 may not be present in one or more embodiments. Anauthorization obtained at one point may authorize only entry to a secureenvironment through a controllable barrier, it may authorize taking andcharging of items, or it may authorize both (as illustrated in FIG. 22).

FIG. 23 shows a variation on the scenario illustrated in FIG. 22, wherea person removes and item from a shelf but then puts it down prior toleaving the store. As in FIG. 22, person 1901 takes item 111 from shelf102. Prior to exiting the store, person 1901 places item 111 back onto adifferent shelf 2301. Using techniques such as those described abovewith respect to FIGS. 3 and 4, processor 130 initially determines takeaction 2304, for example by analyzing images from cameras such as camera202 that observe shelf 102. Afterwards processor 130 determines putaction 2305, for example by analyzing images from cameras such ascameras 2302 and 2303 that observe shelf 2301. The processor thereforedetermines that person 1901 has no items in his or her possession uponleaving the store and transmits message 213 b to a display to confirmthis for the person.

One or more embodiments may enable extending an authorization from oneperson to another person. For example, an authorization may apply to anentire vehicle and therefore may authorize all occupants of that vehicleto perform actions such as entering a secured area or taking andpurchasing products. FIG. 24 illustrates an example that is a variationof the example of FIG. 19. Person 1901 goes to gas pump 1902 to presenta credential to obtain an authorization. Camera 1911 (possibly inconjunction with other cameras) captures images of person 1901 exitingvehicle 2401. Processor 130 analyzes these images and associates person1901 with vehicle 2401. The processor analyzes subsequent images totrack any other occupants of the vehicle that exit the vehicle. Forexample, a second person 2402 exits vehicle 2401 and is detected by thecameras in the gas station. The processor generates a new trajectory2403 for this person and assigns a new tag 2404 to this trajectory.After the authorization of person 1901 is obtained, processor 130associates this authorization with person 2402 (as well as with person1901), since both people exited the same vehicle 2401. When person 2402reaches location 1925 at entry 1908 to store 1903, processor 130 sends acommand 2406 to allow access to the store, since person 2402 isauthorized to enter by extension of the authorization obtained by person1901.

One or more embodiments may query a person to determine whetherauthorization should be extended and if so to what extent. For example,a person may be able to selectively extend authorization to certainlocations, for certain actions, for a certain time period, or toselected other people. FIGS. 25A, 25B and 25C show an illustrativeexample with queries provided at gas pump 1902 when person 1901 presentsa credential for authorization. The initial screen shown in FIG. 25Aasks the user to provide the credential. The next screen shown in FIG.25B asks the user whether to extend authorization to purchases as theattached convenience store; this authorization may for example allowaccess to the store through the locked door and may charge items takenby the user automatically to the user's account. The next screen in FIG.25C asks the user if he or she wants to extend authorization to otheroccupants of the vehicle (as in FIG. 24). These screens and queries areillustrative; one or more embodiments may provide any types of queriesor receive any type of user input (proactively from the user or inresponse to queries) to determine how and whether authorization shouldbe extended. Queries and responses may for example be provided via amobile phone as opposed to on a screen associated with a credentialreader, or via any other device or devices.

Returning now to the tracking technology that tracks people through astore or an area using analysis of camera images, in one or moreembodiments it may be advantageous or necessary to track people usingmultiple ceiling-mounted cameras, such as fisheye cameras with widefields of view (such as 180 degrees). These cameras provide potentialbenefits of being less obtrusive, less visible to people, and lessaccessible to people for tampering. Ceiling-mounted cameras also usuallyprovide unoccluded views of people moving through an area, unlike wallcameras that may lose views of people as they move behind fixtures orbehind other people. Ceiling-mounted fisheye cameras are also frequentlyalready installed, and they are widely available.

One or more embodiments may simultaneously track multiple people throughan area using multiple ceiling-mounted cameras using the technologydescribed below. This technology provides potential benefits of beinghighly scalable to arbitrarily large spaces, inexpensive in terms ofsensors and processing, and adaptable to various levels of detail as thearea or space demands. It also offers the advantage of not needing asmuch training as some deep-learning detection and tracking approaches.The technology described below uses both geometric projection andappearance extraction and matching.

FIGS. 26A through 26F show views from six different ceiling-mountedfisheye cameras installed in an illustrative store. The images arecaptured at substantially the same time. The cameras may for example becalibrated intrinsically and extrinsically, as described above. Thetracking system therefore knows where the cameras are located andoriented in the store, as described for example in a 3D model of thestore. Calibration also provides a mapping from points in the store 3Dspace to pixels in a camera image, and vice-versa.

Tracking directly from fisheye camera images may be challenging, due forexample to the distortion inherent in the fisheye lenses. Therefore, inone or more embodiments, the system may generate a flat planarprojection from each camera image to a common plane. For example, in oneor more embodiments the common plane may be a horizontal plane 1 meterabove the floor or ground of the site. This plane has an advantage thatmost people walking in the store intersect this plane. FIGS. 27A, 27B,and 27C show projections of three of the fisheye images from FIGS. 26Athrough 26F onto this plane. Each point in the common plane 1 meterabove the ground corresponds to a pixel in the planar projections at thesame pixel coordinates. Thus, the pixels at the same pixel coordinatesin each of the image projections onto the common plane, such as theimages 27A, 27B, and 27C, all correspond to the same 3D point in space.However, since the cameras may be two-dimensional cameras that do notcapture depth, the 3D point may be sampled anywhere along the raybetween it and the camera.

Specifically, in one or more embodiments the planar projections 27A, 27Band 27C may be generated as follows. Each fisheye camera may becalibrated to determine the correspondence between a pixel in thefisheye image (such as image 26A for example) and a ray in spacestarting at the focal point of the camera. To project from a fisheyeimage like image 26A to a plane or any other surface in a store or site,a ray may be formed from the camera focal point to that point on thesurface, and the color or other characteristics of the pixel in thefisheye image associated with that ray may be assigned to that point onthe surface.

When an object is at a 1-meter height above the floor, all cameras willsee roughly the same pixel intensities in their respective projectiveplanes, and all patches on the projected 2D images will be correlated ifthere is an object at the 1-meter height. This is similar to the planesweep stereo method known in the art, with the provision that thetechnique described here projects onto a plane that is parallel to thefloor as people will be located there (not flying above the floor).Analysis of the projected 2D images may also take into account thewalkable space of a store or site, and occlusions of some parts of thespace in certain camera images. This information may be obtained forexample from a 3D model of the store or site.

In some situations, it may be possible for points on a person that are1-meter high from the floor to be occluded in one or more fisheye cameraviews by other people or other objects. The use of ceiling-mountedfisheye cameras minimizes this risk, however, since ceiling viewsprovide relatively unobstructed views of people below. For storefixtures or features that are in fixed locations, occlusions may bepre-calculated for each camera, and pixels on the 1-meter planeprojected image for that camera that are occluded by these features orfixtures may be ignored. For moving objects like people in the store,occlusions may not be pre-calculated; however, one or more embodimentsmay estimate these occlusions based on the position of each person inthe store in a previous frame, for example.

To track moving objects, in particular people, one or more embodimentsof the system may incorporate a background subtraction or motion filteralgorithm, masking out the background from the foreground for each ofthe planar projected images. FIGS. 28A, 28B, and 28C show foregroundmasks for the projected planar images 27A, 27B, and 27C, respectively. Awhite pixel shows a moving or non-background object, and a black pixelshows a stationary or background object. (These masks may be noisy, forexample because of lighting changes or camera noise.) The foregroundmasks may then be combined to form mask 28D. Foreground masks may becombined for example by adding the mask values or by binary AND-ing themas shown in FIG. 28D. The locations in FIG. 28D where the combined maskis non-zero show where the people are located in the plane at 1-meterabove the ground.

In one or more embodiments, the individual foreground masks for eachcamera may be filtered before they are combined. For example, a gaussianfilter may be applied to each mask, and the filtered masks may be summedtogether to form the combined mask. In one or more embodiments, athresholding step may be applied to locate pixels in the combined maskwith values above a selected intensity. The threshold may be set to avalue that identifies pixels associated with a person even if somecameras have occluded views of that person.

After forming a combined mask, one or more embodiments of the system mayfor example use a simple blob detector to localize people in pixelspace. The blob detector may filter out shapes that are too large or toosmall to correspond to an expected cross-sectional size of a person at1-meter above the floor. Because pixels in the selected horizontal planecorrespond directly to 3D locations in the store, this process yieldsthe location of the people in the store.

Tracking a person over time may be performed by matching detections fromone time step to the next. An illustrative tracking framework that maybe used in one or more embodiments is as follows:

(1) Match new detections to existing tracks, if any. This may be donevia position and appearance, as described below.

(2) Update existing tracks with matched detections. Track positions maybe updated based on the positions of the matched detections.

(3) Remove tracks that have left the space or have been inactive (suchas false positives) for some period of time.

(4) Add unmatched detections from step (1) to new tracks. The system mayoptionally choose to add tracks only at entry points in the space.

The tracking algorithm outlined above thus maintains the positions intime of all tracked persons.

As described above in step (1) of the illustrative tracking framework,matching detections to tracks may be done based on either or both ofposition and appearance. For example, if a person detection at a nextinstant in time is near the previous position of only one track, thisdetection may be matched to that track based on position alone. However,in some situations, such as a crowded store, it may be more difficult tomatch detections to tracks based on position alone. In these situations,the appearance of persons may be used to assist with matching.

In one or more embodiments, an appearance for a detected person may begenerated by extracting a set of images that have corresponding pixelsfor that person. An approach to extracting these images that may be usedin one or more embodiments is to generate a surface around a person(using the person's detected position to define the location of thesurface), and to sample the pixel values for the 3D points on thesurface for each camera. For example, a cylindrical surface may begenerated around a person's location, as illustrated in FIGS. 29Athrough 29F. These figures show the common cylinder (in red) as seenfrom each camera. The surface normal vectors of the cylinder (or othersurface) may be used to only sample surface points that are visible fromeach camera. For each detected person, a cylinder may be generatedaround a center vertical axis through the person's location (defined forexample as a center of the blob associated with that person in thecombined foreground mask); the radius and height of the cylinder may beset to fixed values, or they may be adapted for the apparent size andshape of the person.

As shown in FIGS. 29A through 29F, a cylindrical surface is localized ineach of the original camera views (FIGS. 26A through 26F) based on theintrinsics/extrinsics of each camera. The points on the cylinder aresampled from each image and form the projections shown in FIGS. 30Athrough 30F. Using surface normal vectors of the cylinders, the systemmay only sample the points that would be visible in each camera, ifthere was an opaque surface of the cylinder. The occluded points aredarkened in FIGS. 30A through 30F. An advantage of this approach is thatthe cylindrical surface provides a corresponding view from each camera,and the views can be combined into a single view, taking into accountthe visibilities at each pixel. Visibility for each pixel in eachcylindrical image for each camera may take into account both the frontand back sides of the cylinder as viewed from the camera, and occlusionby other cylinders around other people. Occlusions may be calculated forexample using a method similar to a graphics pipeline: cylinders closerto the camera may be projected first, and the pixels on the fisheyeimage that are mapped to those cylinders are removed (e.g., set toblack) so that they are not projected onto other cylinders; this processrepeats until all cylinders receive projected pixels from the fisheyeimage. Cylindrical projections from each camera may be combined forexample as follows: back faces may be assigned a 0 weight, and visible,unoccluded pixels may be assigned a 1 weight; the combined image may becalculated as a weighted average for all projections onto the cylinder.Combining the occluded cylindrical projections creates a registeredimage of the tracked person that facilitates appearance extraction. Thecombined registered image corresponding to cylindrical projections 30Athrough 30F is shown in FIG. 30G.

Appearance extraction from image 30G may for example be done byhistograms, or by any other dimensionality reduction method. A lowerdimensional vector may be formed from the composite image of eachtracked person and used to compare it with other tracked subjects. Forexample, a neural network may be trained to take composite cylindricalimages as input, and to output a lower-dimensional vector that is closeto other vectors from the same person and far from vectors from otherpersons. To distinguish between people, vector-to-vector distances maybe computed and compared to a threshold; for example, a distance of 0.0to 0.5 may indicate the same person, and a greater distance may indicatedifferent people. One or more embodiments may compare tracks of peopleby forming distributions of appearance vectors for each track, andcomparing distributions using a distribution-to-distribution measure(such as KL-divergence, for example). A discriminant betweendistributions may be computed to label a new vector to an existingperson in a store or site.

A potential advantage of the technique described above over appearancevector and people matching approaches known in the art is that it may bemore robust in a crowded space, where there are many potentialocclusions of people in the space. By combining views from multiplecameras, while taking into account visibility and occlusions, thistechnique may succeed in generating usable appearance data even incrowded spaces, thereby providing robust tracking. This technique treatsthe oriented surface (cylinder in this example) as the basic samplingunit and generates projections based on visibility of 3D points fromeach camera. A point on a surface is not visible from a camera if thenormal to that surface points away from the camera (dot product isnegative). Furthermore, in a crowded store space, sampling the camerabased on physical rules (visibility and occlusion) and cylindricalprojections from multiple cameras provides cleaner images of individualswithout pixels from other individuals, making the task of identifying orseparating people easier.

FIGS. 31A and 31B show screenshots at two points in time from anembodiment that incorporates the tracking techniques described above.Three people in the store are detected and tracked as they move, usingboth position and appearance. The screenshots show fisheye views 3101and 3111 from one of the fisheye cameras, with the location of eachperson indicated with a colored dot overlaying the person's image. Theyalso show combined masks 3102 and 3112 for the planar projections to theplane 1 meter above the ground, as discussed above with respect to FIG.27D. The brightest spots in combined masks 3102 and 3112 correspond tothe detection locations. As an illustration of tracking, the location ofone of the persons moves from location 3103 at the time corresponding toFIG. 31A to the location 3113 at the subsequent time corresponding toFIG. 31B.

Embodiments of the invention may utilize more complicated models, forexample spherical models for heads, additional cylindrical models forupper and lower arms and/or upper and lower legs as well. Theseembodiments enable more detailed differentiation of users, and may beutilized in combination with gait analysis, speed of movement, anyderivative of position, including velocity acceleration, jerk or anyother frequencies of movement to differentiate users and theirdistinguishing characteristics. In one or more embodiments, thecomplexity of the model may be altered over time or as needed based onthe number of users in a given area for example. Other embodiments mayutilize simple cylindrical or other geometrical shapes per user based onthe available computing power or other factors, including the acceptableerror rate for example.

As an alternative to identifying people in a store by performingbackground subtraction on camera images and combining the resultingmasks, one or more embodiments may train and use a machine learningsystem that processes a set of camera images directly to identifypersons. The input to the system may be or may include the camera imagesfrom all cameras, or all cameras in a relevant area. The output may beor may include an intensity map with higher values indicating a greaterlikelihood that a person is at that location. The machine learningsystem may be trained for example by capturing camera images whilepeople move around the store area, and manually labeling the people'spositions to form training data. Camera images may be used as inputsdirectly, or in one or more embodiments they may be processed, and theprocessed images may be used as inputs. For example, images from ceilingfisheye cameras may be projected onto a plane parallel to the floor, asdescribed above, and the projected images may be used as inputs to themachine learning system.

FIG. 32 illustrates an example of a machine learning system that detectsperson positions in a store from camera images. This illustrativeembodiment has three cameras 3201, 3202, and 3203 in the store 3200. Ata point in time, these three cameras capture images 3211, 3212, and3213, respectively. These three images are input into a machine learningsystem 3220 that has learned (or is learning) to map from the collectionof camera images to an intensity map 3221 of likely person positions inthe store.

In the example shown in FIG. 32, the output of system 3220 is the likelyhorizontal position of persons in the store. Vertical position is nottracked. Although people occupy 3D space, horizontal position isgenerally all that is required to determine where each person is in astore, and to associate item motion with a person. Therefore, theintensity map 3221 maps xy position along the floor of the store into anintensity that represents how likely a person's centroid (or other pointor points of a person) is at that horizontal location. This intensitymap may be represented as a grayscale image, for example, with whiterpixels representing higher probability of a person at that location.

The person detection system illustrated in FIG. 32 represents asignificant simplification over systems that attempt to detect landmarkson a person's body or other features of a person's geometry. A person'slocation is represented only by a single 2D point, possibly with a zonearound this point with a falloff in probability. This simplificationmakes detection potentially more efficient and more robust. Processingpower to perform detection may be reduced using this method, therebyreducing the cost of installation for a system and enabling real-timeperson tracking.

In one or more embodiments, a 3D field of influence volume may beconstructed for a person around the 2D point that represents thatperson's horizontal position. That field of influence volume may then beused to determine which item storage areas a person interacts with andthe times of these interactions. For example, the field of influencevolume may be used as described above with respect to FIG. 10. FIG. 32Ashows an example of generating a 3D field of influence volume from a 2Dlocation of a person, as determined for example by the machine learningsystem 3220 of FIG. 32. In this example, a machine learning system orother system generates 2D location data 3221 d. This data includes andextends the intensity map data 3221 of FIG. 32. From the intensity data,the system estimates a point 2D location for each person in the store.These points are 3231 a for a first shopper, and 3232 for a secondshopper. The 2D point may be calculated for example as the weightedaverage of points in a region surrounding a local maximum of intensity,with weights proportional to the intensity of each point. The firstshopper moves, and the system tracks the trajectory 3230 of thisshopper's 2D location. This trajectory 3230 may for example consist of asequence of locations, each associated with a different time. Forexample, at time ti the first shopper is at location 3231 a, and at timet4 the shopper arrives at 2D point 3231 b. For each 2D point location ofa shopper at different points in time, the system may generate a 3Dfield of influence volume around that point. This field of influencevolume may be a translated copy of a standard shape that is used for allshoppers and for all points in time. For example, in FIG. 32A the systemgenerates a cylinder of a standard height and radius, with the centeraxis of the cylinder passing through the 2D location of the shopper.Cylinder 3241 a for the first shopper corresponds to the field ofinfluence volume at point 3231 a at time ti, and cylinder 3242 for thesecond shopper corresponds to the field of influence volume at point3232. The cylinder is illustrative; one or more embodiments may use anytype of shape for a 3D field of influence volume, including for example,without limitation, a cylinder, a sphere, a cube, a parallelepiped, anellipsoid, or any combinations thereof. The selected shape may be usedfor all shoppers and for all locations of the shoppers. Use of a simple,standardized volume around a tracked 2D location provides significantefficiency benefits compared to tracking the specific location oflandmarks or other features and constructing a detailed 3D shape foreach shopper.

When the first shopper reaches 2D location 3231 b at time t4, the 3Dfield of influence volume 3241 b intersects the item storage area 3204.This intersection implies that the shopper may interact with items onthe shelf, and it may trigger the system to track the shelf to determinemovement of items and to attribute those movements to the first shopper.For example, images of the shelf 3204 before the intersection occurs, orat the beginning of the intersection time period may be compared toimages of the shelf after the shopper moves away and the volume nolonger intersects the shelf, or at the end of the intersection timeperiod.

One or more embodiments may further simplify detection of intersectionsby performing this analysis completely or partially in 2D instead of in3D. For example, a 2D model 3250 of the store may be used, which showsthe 2D location of item storage areas such as area 3254 corresponding toshelf 3204. In 2D, the 3D field of influence cylinders become 2D fieldof influence areas that are circles, such as circles 3251 a and 3251 bcorresponding to cylinders 3241 a and 3241 b in 3D. The intersection of2D field of influence area 3251 b with 2D shelf area 3254 indicates thatthe shopper may be interacting with the shelf, triggering the analysesdescribed above. In one or more embodiments, analyzing fields ofinfluence areas and intersections in 2D instead of 3D may provideadditional efficiency benefits by reducing the amount of computation andmodeling required.

As described above, and as illustrated in FIGS. 26 through 31, in one ormore embodiments it may be advantageous to perform person tracking anddetection using ceiling-mounted cameras, such as fisheye cameras. Cameraimages from these cameras, such as images 26A through 26F, may be usedas inputs to the machine learning system 3220 in FIG. 32. Alternatively,or in addition, these fisheye images may be projected onto one or moreplanes, and the projected images may be inputs to machine learningsystem 3220. Projecting images from multiple cameras onto a common planemay simplify person detection since unoccluded views of a person in theprojected images will overlap at the points where the person intersectsthis plane. This technique is illustrated in FIG. 33, which shows twodome fisheye cameras 3301 and 3302 installed on the ceiling of store3200. Images captured by fisheye cameras 3301 and 3302 are projectedonto an imaginary plane 3310 parallel to the floor of the store, atapproximately waist level for a typical shopper. The projected pixellocations on plane 3310 coincide with actual locations of objects atthis height if they are not occluded by other objects. For example,pixels 3311 and 3312 in fisheye camera images from cameras 3301 and3302, respectively, are projected to the same position 3305 in plane3310, since one of the shoppers intersects plane 3310 at this location.Similarly, pixels 3321 and 3322 are projected to the same position 3306,since the other shopper intersects plane 3310 at this location.

FIGS. 34AB through 37 illustrate this technique of projecting fisheyeimages onto a common plane for an artificially generated scene. FIG. 34Ashows the scene from a perspective view, and FIG. 34B shows the scenefrom a top view. Store 3400 has a floor area between two shelves; twoshoppers 3401 and 3402 are currently in this area. Store 3400 has twoceiling-mounted fisheye cameras 3411 and 3412. (The ceiling of the storeis not shown to simplify illustration). FIG. 35 shows fisheye images3511 and 3512 captured from cameras 3411 and 3412, respectively.Although these fisheye images may be input directly into a machinelearning system, the system would have to learn how to relate theposition of an object in one image to the position of that object inanother image. For example, shopper 3401 appears at location 3513 inimage 3511 from camera 3411, and at a different location 3514 in image3512 from camera 3412. While it may be possible for a machine learningsystem to learn these correspondences, a large amount of training datamay be needed. FIG. 36 shows the projection of the two fisheye imagesonto a common plane, in this case a plane one meter above the floor.Image 3511 is transformed with projection 3601 into image 3611, andimage 3512 is transformed with projection 3601 into image 3612. Theheight of the projection plane in this case is selected to intersect thetorso of most shoppers; in one or more embodiments any plane or planesmay be used for projection. One or more embodiments may project fisheyeimages onto multiple planes at different heights, and may use all ofthese projections as inputs to a machine learning system to detectpeople.

FIG. 37 shows images 3611 and 3612 overlaid onto one another toillustrate that locations of shoppers coincide in these two images. Forillustration, the images are alpha weighted each by 0.5 and then summed.The resulting overlaid image 3701 shows location of overlap 3711 forshopper 3401, and location of overlap 3712 for shopper 3402. Theselocations correspond to the intersection of the projection plane witheach shopper. As described above with respect to FIGS. 27ABC and 28ABCD,in one or more embodiments the intersection areas 3711 and 3712 may beused directly to detect persons, for example via thresholding ofintensity and blob detection. Alternatively, or in addition, theprojected images 3611 and 3612 may be input into a machine learningsystem, as described below.

As illustrated in FIG. 37, the appearance of a person in a camera image,even when this image is projected onto a common plane, varies dependingon the location of the camera. For example, the FIG. 3721 in image 3611is different from the FIG. 3722 in image 3612, although these figuresoverlap in region 3711 in combined image 3701. Because of this cameralocation dependence for images, knowledge of the camera locations mayimprove the ability of a machine learning system to detect people incamera images. The inventors have discovered that an effective techniqueto account for camera location is to extend each projected image with anadditional “channel” that reflects the distance between each associatedpoint on the projected plane and the camera location. Unexpectedly,adding this channel as an input feature may dramatically reduce theamount of training data needed to train a machine learning system torecognize person locations. This technique of projecting camera imagesto a common plane and adding a channel of distance information to eachimage is not known in the art. Encoding distance information as anadditional image channel also has the benefit that a machine learningsystem (such as a convolutional neural network, as described below)organized to process images may be adapted easily to accommodate thisadditional channel as an input.

FIG. 38 illustrates a technique that may be used in one or moreembodiments to generate a camera distance channel associated withprojected images. For each point on the projected plane (such as theplane one meter above the floor), a distance to each camera may bedetermined. These distances may be calculated based on calibrated camerapositions, for example. For instance, at point 3800, which is on theintersection of the projected plane with the torso of shopper 3401,these distances are distance 3801 to camera 3411 and distance 3802 tocamera 3412. Distances may be calculated in any desired metric,including but not limited to a Euclidean metric as shown in FIG. 38.Based on the distance between a camera and each point on the projectedplane, a position weight 3811 may be calculated for each point. Thisposition weight may for example be used by the machine learning systemto adjust the importance of pixels at different positions on an image.The position weight 3811 may be any desired function of the distance3812 between the camera and the position. The illustrative positionweight curve 3813 shown in FIG. 38 is a linear, decreasing function ofdistance, with a maximum weight 1.0 at the minimum distance. Theposition weight may decrease to 0 at the maximum distance, or it may beset to some other desired minimum weight value. One or more embodimentsmay use position weight functions other than linear functions. In one ormore embodiments the position weight may also be a function of othervariables in addition to distance from the camera, such as distance fromlights or obstacles, proximity to shelves or other zones of interest,presence of occlusions or shadows, or any other factors.

Illustrative position weight maps 3821 for camera 3411 and 3822 forcamera 3412 are shown in FIG. 38 as grayscale images. Brighter pixels inthe grayscale images correspond to higher position weights, whichcorrespond to shorter distances between the camera and the position onthe projected plane associated with that pixel.

FIG. 39 illustrates how the position weight maps generated in FIG. 38may be used in one or more embodiments for person detection. Projectedimages 3611 and 3612, from cameras 3411 and 3412, respectively, may beseparated into color channels. FIG. 39 illustrates separating theseimages into RGB color channels; these channels are illustrative, and oneor more embodiments may use any desired decomposition of images intochannels using any color space or any other image processing methods.The RGB channels are combined with a fourth channel representing theposition weight map for the camera that captured the image. The fourchannels for each image are input into machine learning system 3220,which generates an output 3221 a with detection probabilities for eachpixel. Therefore image 3611 corresponds to four inputs 3611 r, 3611 g,3611 b, and 3821; and image 3612 corresponds to four inputs 3612 r, 3612g, 3612 b, and 3822. To simplify the machine learning system, in one ormore embodiments the position weight maps 3821 and 3822 may be scaled tohave the same size as the associated color channels.

Machine learning system 3220 may incorporate any machine learningtechnologies or methods. In one or more embodiments, machine learningsystem 3220 may be or may include a neural network. FIG. 40 shows anillustrative neural network 4001 that may be used in one or moreembodiments. In this neural network, inputs are 4 channels for eachprojected image, with the fourth channel containing position weights asdescribed above. Inputs 4011 represent the four channels from the firstcamera, inputs 4012 represent the four channels from the second camera,and there may be additional inputs 4019 from any number of additionalcameras (also augmented with position weights). By scaling all imagechannels, including the position weights channels, to the same size, allinputs may share the same coordinate system. Thus, for a system with Ncameras, and images of size H×W, the total number of input values forthe network may be N*H*W*4. More generally with C channels per image(including potentially position weights), the total of number of inputsmay be N*H*W*C.

The illustrative neural network 4001 may be for example a fullyconvolutional network with two halves: a first (left) half that is builtout of N copies (for N cameras) of a feature extraction network, whichmay consist of layers of decreasing size; and a second (right) half thatmaps the extracted features into positions. In between the two halvesmay be a feature merging layer 4024, which may for example be an averageover the N feature maps. The first half of the network may have forexample N copies of a standard image classification network. The finalclassifier layer of this image classification network may be removed,and the network may be used as a pre-trained feature extractor. Thisnetwork may be pretrained on a dataset such as the ImageNet dataset,which is a standard objects dataset with images and labels for varioustypes of objects, including but not limited to people. The lower layers(closer to the image) in the network generally mirror the pixelstatistics and primitives. Pretrained weights may be augmented withadditional weights for the position maps, which may be initialized withrandom values. Then the entire network may be trained with manuallylabeled person positions, as described below with respect to FIG. 41.All weights, including the pretrained weights, may vary during trainingwith the labeled dataset. In the illustrative network 4001, the copiesof the image classification network (which extracts image features) are4031, 4032, and 4039. (There may be additional copies if there areadditional cameras.) Each of these copies 4031, 4032, and 4039 may haveidentical weights.

The first half of the network 4031 (and thus also 4032 and 4039) may forexample reduce the spatial size of the feature maps several times. Theillustrative network 4031 reduces the size three times, with the threelayers 4021, 4022, and 4023. For example, for inputs such as input 4011of size H×W×C, the output feature maps of layers 4021, 4022, and 4023may be of sizes H/8×W/8, H/16×W/16, and H/32×W/32, respectively. In thisillustrative network, all C channels of input 4011 are input into layer4021 and are processed together to form output features of size H/8×W/8,which are fed downstream to layer 4022. These values are illustrative;one or more embodiments may use any number of feature extraction layerswith input and output sizes of each layer of any desired dimensions.

The feature merging layer 4024 may be for example an averaging over allof the feature maps that are input into this merging layer. Since inputsfrom all cameras are weighted equally, the number of cameras can changedynamically without changing the network weights. This flexibility is asignificant benefit of this neural network architecture. It allows thesystem to continue to function if one or more cameras are not working.It also allows new cameras to be added at any time without requiringretraining of the system. In addition, the number of cameras used can bedifferent during training compared to during deployment for operationalperson detection. In comparison, person detection systems known in theart may not be robust when cameras change or are not functioning, andthey may require significant retraining whenever the cameraconfiguration of a store is modified.

The output features from the final reduction layer 4023, and theduplicate final reduction layers for the other cameras, are input intothe feature merging layer 4024. In one or more embodiments, featuresfrom one or more previous reduction layers may also be input into thefeature merging layer 4024; this combination may for example provide amixture of lower-level features from earlier layers and higher-levelfeatures from later layers. For example, lower-level features from anearlier layer (or from multiple earlier layers) may be averaged acrosscameras to form a merged lower-level feature output, which may be inputinto the second half network 4041 along with the average of thehigher-level features.

The output of the feature merging layer 4024 (which reduces N sets offeature maps to 1 set) is input into the second half network 4041. Thesecond half network 4041 may for example have a sequence of transposedconvolution layers (also known as deconvolution layers), which increasethe size of the outputs to match the size H×W of the input image. Anynumber of deconvolution layers may be used; the illustrative network4041 has three deconvolution layers 4024, 4026, and 4027.

The final output 3221 a from the last deconvolution layer 4027 may beinterpreted as a “heat map” of person positions. Each pixel in theoutput heat map 3221 a corresponds to an x,y coordinate in the projectedplane onto which all camera images are projected. The output 3221 a isshown as a grayscale image, with brighter pixels corresponding to highervalues of the outputs from neural network 4001. These values may bescaled for example to the range 0.0 to 1.0. The “hot spots” of the heatmap correspond to person detections, and the peaks of the hot spotsrepresent the x,y locations of the centroid of each person. Because thenetwork 4001 does not have perfect precision in detecting the positionof persons, the output heat map may contain zones of higher or moderateintensity around the centroids of the hot spots.

The machine learning system such as neural network 4001 may be trainedusing images captured from cameras that are projected to a plane andthen manually labeled to indicate person positions within the images.This process is illustrated in FIG. 41. A camera image is captured whilepersons are in the store area, and it is projected onto a plane to forman image 3611. A user 4101 reviews this image (as well as other imagescaptured during this session or other sessions, from the same camera orfrom other cameras), and the user manually labels the position of thepersons at the centroid of the area where they intersect the projectionplane. The user 4101 picks points such as 4102 and 4103 for the personlocations. The training system then generates 4104 a probability densitydistribution around the selected points. For example, the distributionin one or more embodiments may be a two-dimensional gaussian of somespecified width centered on the selected points. The target output 4105may be for example the sum of the distributions generated in step 4104at each pixel. One or more embodiments may use any type of probabilitydistribution around the point or points selected by the user to indicateperson positions. The target output 4105 is then combined with camerainputs (and position weights) from all cameras used for training, suchas inputs 4011 and 4012, to form a training sample 4106. This trainingsample is added to a training dataset 4107 that is used to train theneural network.

An illustrative training process that may be used in one or moreembodiments is to have one or more people move through a store, and tosample projected camera images at fixed time intervals (for exampleevery one second). The sampled images may be labeled and processed asillustrated in FIG. 41. On each training iteration a random subset ofthe cameras in an area may be selected to be used as inputs. The planeprojections may also be performed on randomly selected planes parallelto the floor within some height range above the store. In addition,random data augmentation may be performed to generate additionalsamples; for example, synthesized images may be generated to deform theshapes or colors of persons, or to move their images to different areasof the store (and to move the labeled positions accordingly).

Tracking of persons and item movements in a store or other area may useany cameras (or other sensors), including “legacy” surveillance camerasthat may already be present in a store. Alternatively, or in addition,one or more embodiments of the system may include modular elements withcameras and other components that simplify installation, configuration,and operation of an automated store system. These modular components maysupport a turnkey installation of an automated store, potentiallyreducing installation and operating costs. Quality of tracking ofpersons and items may also be improved using modular components that areoptimized for tracking.

FIG. 42 illustrates a store 4200 with modular “smart” shelves that maybe used to detect taking, moving, or placing of items on a shelf. Asmart shelf may for example contain cameras, lighting, processing, andcommunications components in an integrated module. A store may have oneor more cabinets, cases, or shelving units with multiple smart shelvesstacked vertically. Illustrative store 4200 has two shelving units 4210and 4220. Shelving unit 4210 has three smart shelves, 4211, 4212, and4213. Shelving unit 4220 has three smart shelves, 4221, 4222, and 4223.Data may be transmitted from each smart shelf to computer 130, foranalysis of what item or items are moved on each shelf. Alternatively,or in addition, in one or more embodiments each shelving unit may act asa local hub, and may consolidate data from each smart shelf in theshelving unit and forward this consolidated data to computer 130. Theshelving units 4210 and 4220 may also perform local processing on datafrom each smart shelf. In one or more embodiments, an automated storemay be structured for example as a hierarchical system with the entirestore at the top level, “smart” shelving units at the second level,smart shelves at the third level, and components such as cameras orlighting at the fourth level. One or more embodiments may organizeelements in hierarchical structures with any number of levels. Forexample, stores may be divided into regions, with local processingperformed for each region and then forwarded to a top-level storeprocessor.

The smart shelves shown in FIG. 42 have cameras mounted on the bottom ofthe shelf; these cameras observe items on the shelf below. For example,camera 4231 on shelf 4212 observes items on shelf 4213. When user 4201reaches for an item on shelf 4213, cameras on either or both of shelves4212 and 4213 may detect entry of the user's hand into the shelf area,and may capture images of shelf contents that may be used to determinewhich item or items are taken or moved. This data may be combined withimages from other store cameras, such as cameras 4231 and 4232, to trackthe shoppers and attribute item movements to specific shoppers.

FIG. 43 shows an illustrative embodiment of a smart shelf 4212, viewedfrom the front. FIGS. 44 through 47 show additional views of thisembodiment. Smart shelf 4212 has cameras 4301 and 4302 at the left andright ends, respectively, which face inward along the front edge of theshelf. Thus the left end camera 4301 is rightward-facing, and the rightend camera 4302 is leftward-facing. These cameras may be used forexample to detect when a user's hand moves into or out of the shelfarea. These cameras 4301 and 4302 may be used in combination withsimilar cameras on shelves above and/or below shelf 4212 in a shelvingunit (such as shelves 4211 and 4213 in FIG. 42) to detect hand events.For example, the system may use multiple hand detection cameras totriangulate the position of a hand going into a shelf. With two camerasobserving a hand, the position of a hand can be determined from the twoimages. With multiple cameras (for example four or more) observing ashelf, the system may be able to determine the position of more than onehand at a time since the multiple views can compensate for potentialocclusions. Images of the shelf just prior to a hand entry event may becompared to images of the shelf just after a hand exit event, in orderto determine which item or items may have been taken, moved, or added tothe shelf. In one or more embodiments other detection technologies maybe used instead of or in addition to the cameras 4301 and 4302 to detecthand entry and hand exit events for the shelf; these technologies mayinclude for example, without limitation, light curtains, sensors on adoor that must be opened to access the shelf or the shelving unit,ultrasonic sensors, and motion detectors.

Smart shelf 4212 may also have one or more downward-facing cameramodules mounted on the bottom side of the shelf, facing the shelf 4213below. For example, shelf 4214 has camera modules 4311, 4312, 4313, and4314 mounted on the bottom side of the shelf. The number of cameramodules and their positions and orientations may vary acrossinstallations, and also may vary across individual shelves in a store.These camera modules may capture images of the items on the shelf.Changes in these images may be analyzed by the system, by a processor onthe shelf or on a shelving unit, or by both, to determine what itemshave been taken, moved, or added to the shelf below.

FIGS. 44A and 44B show a top view and a side view, respectively, ofsmart shelf 4212. Brackets 4440 may be used for example to attach shelf4212 to a shelving unit; the shape and position of mounting brackets orsimilar attachment mechanisms may vary across embodiments.

FIG. 44C shows a bottom view of smart shelf 4212. All cameras arevisible in this view, including the inside-facing cameras 4301 and 4302,and the downward-facing cameras associated with camera modules 4311,4312, 4313, and 4314. In this illustrative embodiment, each cameramodule contains two cameras: cameras 4311 a and 4311 b in module 4311,cameras 4312 a and 4312 b in module 4312, cameras 4313 a and 4313 b inmodule 4313, and cameras 4314 a and 4314 b in module 4314. Thisconfiguration is illustrative; camera modules may contain any number ofcameras. Use of two or more cameras per camera module may assist withstereo vision, for example, in order to generate a 3D view of the itemson the shelf below, and a 3D representation of the changes in shelfcontents when a user interacts with items on the shelf.

Shelf 4212 also contains light modules 4411, 4412, 4413, 4414, 4415, and4416. These light modules may be LED light strips, for example.Embodiments of a smart shelf may contain any number of light modules, inany locations. The intensity, wavelengths, or other characteristics ofthe light emitted by the light modules may be controlled by a processoron the smart shelf. This control of lighting may enhance the ability ofthe camera modules to accurately detect item movements and to captureimages that allow identification of the items that have moved. Lightingcontrol may also be used to enhance item presentation, or to highlightcertain items such as items on sale or new offerings.

Smart shelf 4212 contains integrated electronics, including a processorand network switches. In the illustrative smart shelf 4212, theseelectronics are contained in areas 4421 and 4422 at the ends of theshelf. One or more embodiments may locate any components at any positionon the shelf. FIG. 45 shows a bottom view smart shelf 4212 with thecovers to electronics areas 4421 and 4422 removed, to show thecomponents. Two network switches 4501 and 4503 are included; theseswitches may provide for example connections to each camera and to eachlighting module, and a connection between the smart shelf and the storecomputer or computers. A processor 4502 is included; it may be forexample a Raspberry Pi® or similar embedded computer. Power supplies4504 may also be included; these power supplies may provide AC to DCpower conversion for example.

FIG. 46A shows a bottom view of a single camera module 4312. This moduleprovides a mounting bracket onto which multiple cameras may be mountedin any desired positions. Camera positions and numbers may be modifiedbased on characteristics such as item size, number of items, anddistance between shelves. The bracket has slots 4601 a, 4602 a, 4603 aon the left, and corresponding slots 4601 b, 4602 b, and 4603 b on theright. Individual cameras may be installed at any desired position inany of these slots. Positions of cameras may be adjusted after initialinstallation. Camera module 4312 has two cameras 4312 a and 4312 binstalled in the top and bottom slot pairs; the center slot pair 4602 aand 4602 b is unoccupied in this illustrative embodiment. FIG. 46B showsan individual camera 4312 a from a side view. Screw 4610 is insertedthrough one of the slots on the bracket 4312 to install the camera; acorresponding screw on the far side of the camera attaches the camera tothe opposing slot in the bracket.

FIG. 47 illustrates how camera modules and lighting modules may beinstalled at any desired positions in smart shelf 4212. Additionalcamera modules and lighting modules may also be added in any availablepositions, and positions of installed components may be adjusted. Thesemodules mount to a rail 4701 at one end of the shelf (and to acorresponding rail at the other end, which is not shown in FIG. 47).This rail 4701 has slots into which screws are attached to hold endbrackets of the modules against the rail. For example, lighting module4413 has an end bracket 4703, and screw 4702 attaches through this endbracket into a groove in rail 4701. Similar attachments are used toattach other modules such as camera module 4312 and lighting module4412.

One or more embodiments may include a modular, “smart” ceiling thatincorporates cameras, lighting, and potentially other components atconfigurable locations on the ceiling. FIG. 48 shows an illustrativeembodiment of a store 4800 with a smart ceiling 4801. This illustrativeceiling has a center longitudinal rail 4821 onto which transverse rails,such as rail 4822, may be attached at any desired locations. Lightingand camera modules may be attached to the transverse rails at anydesired locations. This combined longitudinal and transverse railingsystem provides complete two degree of freedom positioning for lightsand cameras. In the configuration shown in FIG. 48, three transverserails 4822, 4823, and 4824 each hold two integrated lighting-cameramodules. For example, transverse rail 4823 holds integratedlighting-camera module 4810, which contains a circular light strip 4811,and two cameras 4812 and 4813 in the central area inside the circularlight strip. In one or more embodiments, the rails or other mountingmechanisms of the ceiling may hold any type or types of lighting orcamera components, either integrated like module 4810 or standalone. Therail configuration shown in FIG. 48 is illustrative; one or moreembodiments may provide any type of lighting-camera mounting mechanismsin any desired configuration. For example, mounting rails or othermounting mechanisms may be provided in any desired geometry, not limitedto the longitudinal and transverse rail configuration illustrated inFIG. 48.

Data from ceiling 4801 may be transmitted to store computer 130 foranalysis. In one or more embodiments, ceiling 4801 may contain one ormore network switches, power supplies, or processors, in addition tocameras and lights. Ceiling 4801 may perform local processing of datafrom cameras before transmitting data to the central store computer 130.Store computer 130 may also transmit commands or other data to ceiling4801, for example to control lighting or camera parameters.

The embodiment illustrated in FIG. 48 has a modular smart ceiling 4801as well as modular shelving units 4210 and 4220 with smart shelves. Datafrom ceiling 4801 and from shelves in 4210 and 4220 may be transmittedto store computer 130 for analysis. For example, computer 130 mayprocess images from ceiling 4801 to track persons in the store, such asshopper 4201, and may process images from shelves in 4210 and 4220 todetermine what items are taken, moved, or placed on the shelves. Bycorrelating person positions with shelf events, computer 130 maydetermine which shoppers take items, thereby supporting a fully orpartially automated store. The combination of smart ceiling and smartshelves may provide a partially or fully turnkey solution for anautomated store, which may be configured based on factors such as thestore's geometry, the type of items sold, and the capacity of the store.

FIG. 49 shows an embodiment of a modular ceiling similar to the ceilingof FIG. 48. A central longitudinal rail 4821 a provides a mountingsurface for transverse rails 4822 a, 4822 b, and 4822 c, which in turnprovide mounting surfaces for integrating lighting-camera modules. Thetransverse rails may be located at any points along longitudinal rail4821 a. Any number of transverse rails may be attached to thelongitudinal rail. Any number of integrated lighting-camera modules, orother compatible modules, may be attached to the transverse rails at anypositions. Transverse rail 4822 a has two lighting-camera modules 4810 aand 4810 b, and transverse rail 4822 b has three lighting-camera modules4810 c, 4810 d, and 4810 e. The positions of the lighting-camera modulesvary across the three transverse rails to illustrate the flexibility ofthe mounting system.

FIG. 50 shows a closeup view of transverse rail 4822 a andlighting-camera module 4810 a. Transverse rail 4822 a has a crossbar5022 with a C-shaped attachment 5001 that clamps around a correspondingprotrusion on rail 4821 a. The position of the transverse rail 4822 a isadjustable along the longitudinal rail 4821 a. Lighting-camera module4810 a has a circularly shaped annular light 5011 with a pair of cameras5012 and 5013 in a central area surrounded by the light 5011. The twocameras 5012 and 5013 may be used for example to provide stereo vision.Alternatively, or in addition, two or more cameras per lighting-cameramodule may provide redundancy so that person tracking can continue evenif one camera is down. The circular shape of light 5011 provides adiffuse light that may improve tracking by reducing reflections andimproving lighting consistency across a scene. This circular shape isillustrative; one or more embodiments may use lights of any size orshape, including for example, without limitation, any polygonal orcurved shape. Lights may be for example triangular, square, rectangular,pentagonal, hexagonal, or shaped like any regular or irregular polygon.In one or more embodiments lights may consist of multiple segments ormultiple polygons or curves. In one or more embodiments, a light maysurround a central area without lighting elements, and one or morecameras may be placed in this central area.

In one or more embodiments the light elements such as light 5011 may becontrollable, so that the intensity, wavelength, or othercharacteristics of the emitted light may be modified. Light may bemodified for example to provide consistent lighting throughout the dayor throughout a store area. Light may be modified to highlight certainsections of a store. Light may be modified based on camera imagesreceived by the cameras coupled to the light elements, or based on anyother camera images. For example, if the store system is havingdifficulty tracking shoppers, modification of emitted light may improvetracking by enhancing contrast or by reducing noise.

FIG. 51 shows a closeup view of integrated lighting-camera module 4810a. A bracket system 5101 connects to light 5011 (at two sides) and tothe two cameras 5012 and 5013 in the center of the light, and thisbracket 5101 has connections to rail 4822 a that may be positioned atany points along the rail. The center horizontal section 5102 of thebracket system 5101 provides mounting slots for the cameras, such asslot 5103 into which camera mount 5104 for camera 5013 is mounted; theseslots allow the number and position of cameras to be modified as needed.In one or more embodiments this central camera mounting bracket 5102 maybe similar to or identical to the shelf camera mounting bracket shown inFIG. 46A, for example. In one or more embodiments, ceiling cameras suchas camera 5013 may also be similar to or identical to the shelf camerassuch as camera 4312 a shown in FIG. 46A. Use of similar or identicalcomponents in both smart shelves and smart ceilings may further simplifyinstallation, operation, and maintenance of an automated store, and mayreduce cost through use of common components.

Automation of a store may incorporate three general types of processes,as illustrated in FIG. 52 for store 4800: (1) tracking the movements5201 of shoppers such as 4201 through the store, (2) tracking theinteractions 5202 of shoppers with item storage areas such as shelf4213, and (3) tracking the movement 5203 of items, when shoppers takeitems from the shelf, put them back, or rearrange them. In theillustrative automated store 4800 shown in FIG. 52, these three trackingprocesses are performed using combinations of cameras and processors.For example, movement 5201 of shoppers may be tracked by ceiling camerassuch as camera 4812. A processor or processors 130 may analyze imagesfrom these ceiling cameras using for example methods described abovewith respect to FIGS. 26 through 41. Interactions 5202 and itemmovements 5203 may be tracked for example using cameras integrated intoshelves or other storage fixtures, such as camera 4231. Analysis ofthese images may be performed using either or both of store processors130 and processors such as 4502 integrated into shelves. One or moreembodiments may use combinations of these techniques; for example,ceiling cameras may also be used to track interactions or item movementswhen they have unobstructed views the item storage areas.

FIGS. 53 through 62 describe methods and systems that may be used in oneor more embodiments to perform tracking of interactions and itemmovements. FIGS. 53A and 53B show an illustrative scenario that is usedas an example to describe these methods and systems. FIG. 53B shows anitem storage area before a shopper reaches into the shelf with hand5302, and FIG. 53A shows this item storage area after the shopperinteracts with the shelf to remove items. The entire item storage area5320 is the volume between shelves 4213 and 4212. Detection of theinteraction of hand 5302 with this item storage area may be performedfor example by analyzing images from side-facing cameras 4301 and 4302on shelf 4212. Side-facing cameras from other shelves may also be used,such as the cameras 5311 and 5312 on shelf 4213. In one or moreembodiments other sensors may be used instead of or in addition tocameras to detect the interaction of the shopper with the item storagearea. Typically the shopper interacts with an item storage area byreaching a hand 5302 into the area; however, one or more embodiments maytrack any type of interaction of a shopper with an item storage area,via any part of the shopper's body or any instrument or tool the shoppermay use to reach into the area or otherwise interact with items in thearea.

Item storage area 5320 contains multiple items of different types. Inthe illustrative interaction, the shopper reaches for the stack of items5301 a, 5301 b, and 5301 c, and removes two items 5301 b and 5301 c fromthe stack. Determination of which item or items a shopper has removedmay be performed for example by analyzing images from cameras on theupper shelf 4212 which face downward into item storage area 5320. Theseanalyses may also determine that a shopper has added one or more items(for example by putting an item back, or by moving it from one shelf toanother), or has displaced items on the shelf. Cameras may include forexample the cameras in camera modules 4311, 4312, 4313, and 4314.Cameras that observe the item storage area to detect item movement arenot limited to those on the bottom of a shelf above the item storagearea; one or more embodiments may use images from any camera or camerasmounted in any location in the store to observe the item storage areaand detect item movement.

Item movements may be detected by comparing “before” and “after” imagesof the item storage area. In some situations, it may be beneficial tocompare before and after images from multiple cameras. Use of multiplecameras in different locations or orientations may for example supportgeneration of a three-dimensional view of the changes in items in theitem storage area, as described below. This three-dimensional view maybe particularly valuable in scenarios such as the one illustrated inFIGS. 53A and 53B, where the item storage area has a stack of items. Forexample, the before and after images comparing stack 5301 a, 5301 b, and5301 c to the single “after” item 5301 a may look similar from a singlecamera located directly above the stack; however, views from cameras indifferent locations may be used to determine that the height of thestack has changed.

Constructing a complete three-dimensional view of the before and aftercontents of an item storage area may be done for example using anystereo or multi-view vision techniques known in the art. One suchtechnique that may be used in one or more embodiments is plane-sweepstereo, which projects images from multiple cameras onto multiple planesat different heights or at different positions along a sweep axis. (Thesweep axis is often but not necessarily vertical.) While this techniqueis effective at constructing 3D volumes from 2D images, it may becomputationally intensive to perform for an entire item storage area.This computational cost may significantly add to power expenses foroperating an automated store. It may also introduce delays into theprocess of identifying item movements and associating these movementswith shoppers. To address these issues, the inventors have discoveredthat an optimized process can effectively generate 3D views of thechanges in an item storage area with significantly lower computationalcosts. This optimized process performs relatively inexpensive 2D imagecomparisons to identify regions where items may have moved, and thenperforms plane sweeping (or a similar algorithm) only in these regions.This optimization may dramatically reduce power consumption and delays;for example, whereas a full 3D reconstruction of an entire shelf maytake 20 seconds, an optimized reconstruction may take 5 seconds or less.The power costs for a store may also be reduced, for example fromthousands of dollars per month to several hundred. Details of thisoptimized process are described below.

Some embodiments or installations may not perform this optimization, andmay instead perform a full 3D reconstruction of before and aftercontents of an entire item storage area. This may be feasible ordesirable for example for a very small shelf or if power consumption orcomputation time are not concerns.

FIG. 54 shows a flowchart of an illustrative sequence of steps that maybe used in one or more embodiments to identify items in an item storagearea that move. These steps may be reordered, combined, rearranged, orotherwise modified in one or more embodiments; some steps may be omittedin one or more embodiments. These steps may be executed by any processoror combination or network of processors, including for example, withoutlimitation, processors integrated into shelves or other item storageunits, store processors that process information from across the storeor in a region in the store, or processors remote from the store. Steps5401 a and 5401 b obtain camera images from the multiple cameras thatobserve the item storage area. Step 5401 b obtains a “before” image fromeach camera, which was captured prior to the start of the shopper'sinteraction with the item storage area; step 5401 a obtains an “after”image from each camera, after this interaction. (The discussion belowwith respect to FIG. 55 describes these image captures in greaterdetail.) Thus, if there are C cameras observing the item storage area,2C images are obtained—C “before” images and C “after” images.

Steps 5402 b and 5402 a project the before and after images,respectively, from each camera onto surfaces in the item storage area.These projections may be similar for example to the projections ofshopper images described above with respect to FIG. 33. The cameras thatobserve the item storage area may include for example fisheye camerasthat capture a wide field of view, and the projections may map thefisheye images onto planar images. The surfaces onto which images areprojected may be surfaces of any shapes or orientations. In the simplestscenario, the surfaces may be for example parallel planes at differentheights above a shelf. The surfaces may also be vertical planes, slantedplanes, or curved surfaces. Any number of surfaces may be used. If thereare C cameras observing the item storage area, and images from thesecameras are each projected onto S surfaces, then after steps 5202 a and5402 b there will be C×S projected after images and C×S projected beforeimages, for a total of 2C×S projected images.

Step 5403 then compares the before and after projected images.Embodiments may use various techniques to compare images, such as pixeldifferencing, feature extraction and feature comparison, or input ofimage pairs into a machine learning system trained to identifydifferences. The result of step 5403 may be C×S image comparisons, eachcomparing before and after images from a single camera projected to asingle surface. These comparisons may then be combined across cameras instep 5404 to identify a change region for each surface. The changeregion for a surface may be for example a 2D portion of that surfacewhere multiple camera projections to that 2D portion indicate a changebetween the before and after images. It may represent a rough boundaryaround a region where items may have moved. Generally, the C×S imagecomparisons will be combined in step 5404 into S change regions, oneassociated with each surface. Step 5405 then combines the S changeregions into a single change volume in 3D space within the item storagearea. This change volume may be for example a bounding box or othershape that contains all of the S change regions.

Steps 5406 b and 5406 a then construct before and after 3D surfaces,respectively, within the change volume. These surfaces represent thesurfaces of the contents of the item storage area within the changevolume before and after the shopper interaction with the items. The 3Dsurfaces may be constructed using a plane-sweep stereo algorithm or asimilar algorithm that determines 3D shape from multiple camera views.Step 5407 then compares these two 3D surfaces to determine the 3D volumedifference between the before contents and the after contents. Step 5408then checks the sign of the volume change: if volume is added from thebefore to the after 3D surface, then one or more items have been put onthe shelf; if volume is deleted, then one or more items have been takenfrom the shelf.

Images of the before or after contents of the 3D volume difference maythen be used to determine what item or items have been taken or added.If volume has been deleted, then step 5409 b extracts a portion of oneor more projected before images that intersect the deleted volumeregion; similarly, if volume has been added, then step 5409 a extracts aportion of one or more projected after images that intersect the addedvolume region. The extracted image portion or portions may then be inputin step 5410 into an image classifier that identifies the item or itemsremoved or added. The classifier may have been trained on images of theitems available in the store. In one or more embodiments the classifiermay be a neural network; however, any type of system that maps imagesinto item identities may be used.

In one or more embodiments, the shape or size of the 3D volumedifference, or any other metrics derived from the 3D volume difference,may also be input into the item classifier. This may aid in identifyingthe item based on its shape or size, in addition to its appearance incamera images.

The 3D volume difference may also be used to calculate in step 5411 thequantity of items added or removed from the item storage area. Thiscalculation may occur after identifying the item or items in step 5410,since the volume of each item may be compared with the total volumeadded or removed to calculate the item quantity.

The item identity determined in step 5410 and the quantity determined instep 5411 may then be associated in step 5412 with the shopper whointeracted with the item storage area. Based on the sign 5408 of thevolume change, the system may also associate an action such as put,take, or move with the shopper. Shoppers may be tracked through thestore for example using any of the methods described above, andproximity of a shopper to the item storage area during the interactiontime period may be used to identify the shopper to associate with theitem and the quantity.

FIG. 55 illustrates components that may be used to implement steps 5401a and 5401 b of FIG. 55, to obtain after images and before images fromthe cameras. Acquisition of before and after images may be triggered byevents generated by one or more sensor subsystems 5501 that detect whena shopper enters or exits an item storage area. Sensors 5501 may forexample include side-facing cameras 4301 and 4302, in combination with aprocessor or processors that analyze images from these cameras to detectwhen a shopper reaches into or retracts from an item storage area.Embodiments may use any type or types of sensors to detect entry andexit, including but not limited to cameras, motion sensors, lightscreens, or detectors coupled to physical doors or other barriers thatare opened to enter an item storage area. For the camera sensors 4301and 4302 illustrated in FIG. 55, images from these cameras may forexample be analyzed by processor 4502 that is integrated into the shelf4212 above the item storage area, by store processor 130, or by acombination of these processors. Image analysis may for example detectchanges and look for the shape or size of a hand or arm.

The sensor subsystem 5501 may generate signals or messages when eventsare detected. When the sensor subsystem detects that a shopper hasentered or is entering an item storage area, it may generate an entersignal 5502, and when it detects that the shopper has exited or isexiting this area, it may generate an exit signal 5503. Entry maycorrespond for example to a shopper reaching a hand into a space betweenshelves, and exit may correspond to the shopper retracting the hand fromthis space. In one or more embodiments these signals may containadditional information, such as for example the item storage areaaffected, or the approximate location of the shopper's hand. The enterand exit signals trigger acquisition of before and after images,respectively, captured by the cameras that observe the item storage areawith which the shopper interacts. In order to obtain images prior to theenter signal, camera images may be continuously saved in a buffer. Thisbuffering is illustrated in FIG. 55 for three illustrative cameras 4311a, 4311 b, and 4312 a mounted on the underside of shelf 4212. Framescaptured by these cameras are continuously saved in circular buffers5511, 5512, and 5513, respectively. These buffers may be in a memoryintegrated into or coupled to processor 4502, which may also beintegrated into shelf 4212. In one or more embodiments, camera imagesmay be saved to a memory located anywhere, including but not limited toa memory physically integrated into an item storage area shelf orfixture. For the architecture illustrated in FIG. 55, frames arebuffered locally in the shelf 4212 that also contains the cameras; thisarchitecture limits network traffic between the shelf cameras anddevices elsewhere in the store. The local shelf processor 4502 managesthe image buffering, and it may receive the enter signal 5502 and exitsignals 5503 from the sensor subsystem. In one or more embodiments, theshelf processor 4502 may also be part of the sensor subsystem, in thatthis processor may analyze images from the side cameras 4301 and 4302 todetermine when the shopper enters or exits the item storage area.

When the enter and exit signals are received by a processor, for exampleby the shelf processor 4502, the store server 130, or both, theprocessor may retrieve before images 5520 b from the saved frames in thecircular buffers 5511, 5512, and 5513. The processor may lookback priorto the enter signal any desired amount of time to obtain before images,limited only by the size of the buffers. The after images 5520 a may beretrieved after the exit signal, either directly from the cameras orfrom the circular buffers. In one or more embodiments, the before andafter images from all cameras may be packaged together into an eventdata record, and transmitted for example to a store server 130 foranalyses 5521 to determine what item or items have been taken from orput onto the item storage area as a result of the shopper's interaction.These analyses 5521 may be performed by any processor or combination ofprocessors, including but not limited to shelf processors such as 4502and store processors such as 130.

Analyses 5521 to identify items taken, put, or moved from the set ofbefore and after images from the cameras may include projection ofbefore and after images onto one or more surfaces. The projectionprocess may be similar for example to the projections described abovewith respect to FIGS. 33 through 40 to track people moving through astore. Cameras observing an item storage area may be, but are notlimited to, fisheye cameras. FIGS. 56B and 56A show projection of beforeand after images, respectively, from camera 4311 a onto two illustrativesurfaces 5601 and 5602 in the item storage area illustrated in FIGS. 53Band 53A. Two surfaces are shown for ease of illustration; images may beprojected onto any number of surfaces. In this example, the surfaces5601 and 5602 are planes that are parallel to the item storage shelf4213, and are perpendicular to axis 5620 a that sweeps from this shelfto the shelf above. Surfaces may be of any shape and orientation; theyare not necessarily planar nor are they necessarily parallel to a shelf.Projections may map pixels along rays from the camera until theyintersect with the surface of projection. For example, pixel 5606 at theintersection of ray 5603 with projected plane 5601 has the same color inboth the before projected image in FIG. 56B and the after projectedimage in FIG. 56A, because object 5605 is unchanged on shelf 4213 fromthe before state to the after state. However, pixel 5610 b in plane 5602along ray 5604 in FIG. 56B reflects the color of object 5301 c, butpixel 5610 a in plane 5602 reflects the color of the point 5611 of shelf4213, since item 5301 c is removed between the before state and theafter state.

Projected before and after images may be compared to determine anapproximate region in which items may have been removed, added, ormoved. This comparison is illustrated in FIG. 57A. Projected beforeimage 5701 b is compared to projected after image 5701 a; these imagesare both from the same camera, and are both projected to the samesurface. One or more embodiments may use any type of image comparison tocompare before and after images. For example, without limitation, imagecomparison may be a pixel-wise difference, a cross-correlation ofimages, a comparison in the frequency domain, a comparison of one imageto a linear transformation of another, comparisons of extractedfeatures, or a comparison via a trained machine learning system that istrained to recognize certain types of image differences. FIG. 57Aillustrates a simple pixel-wise difference operation 5403, which resultsin a difference image 5702. (Black pixels illustrate no difference, andwhite pixels illustrate a significant difference.) The difference 5702may be noisy, due for example to slight variations in lighting betweenbefore and after images, or to inherent camera noise. Therefore, one ormore embodiments may apply one or more operations 5704 to process theimage difference to obtain a difference region. These operations mayinclude for example, without limitation, linear filtering, morphologicalfiltering, thresholding, and bounding operations such as findingbounding boxes or convex hulls. The resulting difference 5705 contains achange region 5706 that may be for example a bounding box around theirregular and noisy area of region 5703 in the original difference image5702.

FIG. 57B illustrates image differencing on before projected image 5711 band after projected image 5711 a captured from an actual sample shelf.The difference image 5712 has a noisy region 5713 that is filtered andbounded to identify a change region 5716.

Projected image differences, using any type of image comparison, may becombined across cameras to form a final difference region for eachprojected surface. This process is illustrated in FIG. 58. Three cameras5801, 5802, and 5803 capture images of an item storage area before andafter a shopper interaction, and these images are projected onto plane5804. The differences between the projected before and after images are5821, 5822, and 5823 for cameras 5801, 5802, and 5803, respectively.While these differences may be combined directly (for example byaveraging them), one or more embodiments may further weight thedifferences on a pixel basis by a factor that reflects the distance ofeach projected pixel to the respective camera. This process is similarto the weighting described above with respect to FIG. 38 for weightingof projected images of shoppers for shopper tracking. Illustrative pixelweights associated with images 5821, 5822, and 5823 are 5811, 5812, and5813, respectively. Lighter pixels in the position weight imagesrepresent higher pixel weights. The weights may be multiplied by theimage differences, and the products may be averaged in operation 5831.The result may then be filtered or otherwise transformed in operation5704, resulting in a final change region 5840 for that projected plane5804.

After calculating difference regions in various projected planes orother surfaces, one or more embodiments may combine these change regionsto create a change volume. The change volume may be a three-dimensionalvolume within the item storage area within which one or more itemsappear to have been taken, put, or moved. Change regions in projectedsurfaces may be combined in any manner to form a change volume. In oneor more embodiments, the change volume may be calculated as a boundingvolume that contains all of the change regions. This approach isillustrated in FIG. 59, where change region 5901 in projected plane5601, and change region 5902 in projected plane 5602, are combined toform change volume 5903. In this example the change volume 5903 is athree-dimensional box whose extent in the horizontal direction is themaximum extent of the change regions of the projected planes, and whichspans the vertical extent of the item storage area. One or moreembodiments may generate change volumes of any shape or size.

A detailed analysis of the differences in the change volume from thebefore state to the after state may then be performed to identify thespecific item or items added, removed, or moved in this change volume.In one or more embodiments, this analysis may include construction of 3Dsurfaces within the change volume that represent the contents of theitem storage area before and after the shopper interaction. These 3Dbefore and after surfaces may be generated from the multiple cameraimages of the item storage area. Many techniques for construction of 3Dshapes from multiple camera images of a scene are known in the art;embodiments may use any of these techniques. One technique that may beused is plane-sweep stereo, which projects camera images onto a sequenceof multiple surfaces, and locates patches of images that are correlatedacross cameras on a particular surface. FIG. 60 illustrates thisapproach for the example from FIGS. 53A and 53B. The bounding 3D changevolume 5903 is swept with multiple projected planes or other surfaces;in this example the surfaces are planes parallel to the shelf. Forexample, from the top, successive projected planes are 6001, 6002, and6003. The projected planes or surfaces may be the same as or differentfrom the projected planes or surfaces used in previous steps to locatechange regions and the change volume. For example, sweeping of thechange volume 5903 may use more planes or surfaces to obtain a finerresolution estimate of the before and after 3D surfaces. Sweeping of thebefore contents 6000 b of the item storage within the change volume 5903generates 3D before surface 6010 b; sweeping of the after contents 6000a within the change volume 5903 generates 3D after surface 6010 a. Step5406 then calculates the 3D volume difference between these before andafter 3D surfaces. This 3D volume difference may be for example the 3Dspace between the two surfaces. The sign or direction of the 3D volumedifference may indicate whether items have been added or removed. In theexample of FIG. 60, after 3D surface 6010 a is below before 3D surface6010 b, which indicates that an item or items have been removed. Thus,the volume deleted 6011 between the surfaces 6010 b and 6010 a is thevolume of items removed.

FIG. 61 shows an example of plane-sweep stereo applied to a sample shelfcontaining items of various heights. Images 6111, 6112, and 6113 eachshow two projected images from two different cameras superimposed on oneanother. The projections are taken at different heights: images 6111 areat projected to the lowest height 6101 at shelf level; images 6112 areprojected to height 6102; and images 6113 are projected to height 6103.At each projected height, patches of the two superimposed images thatare in focus (in that they match) represent objects whose surfaces areat that projected height. For example, patch 6121 of superimposed images6111 is in focus at the height 6101, as expected since these images showthe shelf itself. Patch 6122 is in focus in superimposed images 6112, sothese objects are at height 6102; and patch 6123 is in focus insuperimposed images 6113, so this object (which is a top lid of one ofthe containers) is at height 6103.

The 3D volume difference indicates the location of items that have beenadded, removed, or moved; however, it does not directly provide theidentity of these items. In some situations, the position of items on ashelf or other item storage area may be fixed, in which case thelocation of the volume difference may be used to infer the item or itemsaffected. In other situations, images of the area of the 3D volumedifference may be used to determine the identity of the item or itemsinvolved. This process is illustrated in FIG. 62. Images from one ormore cameras may be projected onto a surface patch 6201 that intersects3D volume difference 6011. This surface patch 6201 may be selected to beonly large enough to encompass the intersection of the projected surfacewith the volume difference. In one or more embodiments, multiple surfacepatches may be used. Projected image 6202 (or multiple such images) maybe input into an item classifier 6203, which for example may have beentrained or programmed to recognize images of items available in a storeand to output the identity 6204 of the item.

The size and shape of the 3D volume difference 6011 may also be used todetermine the quantity of items added to or removed from an item storagearea. Once the identity 6204 of the item is determined, the size 6205 ofa single item may be compared to the size 6206 of the 3D volumedifference. The item size for example may be obtained from a database ofthis information for the items available in the store. This comparisonmay provide a value 6207 for the quantity of items added, removed, ormoved. Calculations of item quantities may use any features of the 3Dvolume difference 6011 and of the item, such as the volume, dimensions,or shape.

Instead of or in addition to using the sign of the 3D volume differenceto determine whether a shopper has taken or placed items, one or moreembodiments may process before and after images together tosimultaneously identify the item or items moved and the shopper's actionon that item or those items. Simultaneous classification of items andactions may be performed for example using a convolutional neuralnetwork, as illustrated in FIG. 63. Inputs to the convolutional neuralnetwork 6310 may be for example portions of projected images thatintersect change regions, as described above. Portions of both beforeand after projected images from one or more cameras may be input to thenetwork. For example, a stereo pair of cameras that is closest to thechange region may be used. One or more embodiments may use before andafter images from any number of cameras to classify items and actions.In the example shown in FIG. 63, before image 6301 b and after image6301 a from one camera, and before image 6302 b and after image 6302 afrom a second camera are input into the network 6310. The inputs may befor example crops of the projected camera images that cover the changeregion.

Outputs of network 6310 may include an identification 6331 of the itemor items displaced, and an identification 6332 of the action performedon the item or items. The possible actions may include for example anyor all of “take,” “put”, “move”, “no action”, or “unknown.” In one ormore embodiments, the neural network 6310 may perform some or all of thefunctions of steps 5405 through 5411 from the flowchart of FIG. 54, byoperating directly on before and after images and outputting items andactions. More generally, any or all of the steps illustrated in FIG. 54between obtaining of images and associating items, quantities, andactions with shoppers may be performed by one or more neural networks.An integrated neural network may be trained end-to-end for example usingtraining datasets of sample interactions that include before and aftercamera images and the items, actions, and quantities involved in aninteraction.

One or more embodiments may use a neural network or other machinelearning systems or classifiers of any type and architecture. FIG. 63shows an illustrative convolutional neural network architecture that maybe used in one or more embodiments. Each of the image crops 6301 b, 6301a, 6302 b, and 6302 a is input into a copy of a feature extractionlayer. For example, an 18-layer ResNet network 6311 b may be used as afeature extractor for before image 6301 b, and an identical 18-layerResNet network 6311 a may be used as a feature extractor for after image6301 a, with similar layers for the inputs from other cameras. Thebefore and after feature map pairs may then be subtracted, and thedifference feature maps may be concatenated along the channel dimension,in operation 6312 (for the camera 1 before and after pairs, with similarsubtraction and concatenation for other cameras). In an illustrativenetwork, after concatenation the number of channels may be 1024. Aftermerging the feature maps, there may be two or more convolutional layers,such as layers 6313 a and 6313 b, followed by two parallel fullyconnected layers 6321 for item identification and 6322 for actionclassification. The action classifier 6322 has outputs for the possibleactions, such as “take,” “place”, or “no action”. The item classifierhas outputs for the possible products available in the store. Thenetwork may be trained end-to-end, starting for example with pre-trainedImageNet weights for the ResNet layers.

In one or more embodiments, camera images may be combined with data fromother types of sensors to track items taken, replaced, or moved by ashopper. FIG. 64 shows an illustrative store 6400 that utilizes thisapproach. This illustrative store has ceiling cameras such as camera4812 for tracking of shoppers such as shopper 4201. Shelving unit 4210has sensors in sensor bars 6412 and 6413 associated with shelves 4212and 4213, respectively; these sensors may detect shopper actions such astaking or replacing items on the shelves. Each sensor may track items inan associated storage zone of a shelf; for example, sensor 6402 a maytrack items in storage zone 6401 a of shelf 4213. Sensors need not beassociated one-to-one with storage zones; for example, one sensor maytrack actions in multiple storage zones, or multiple sensors may be usedto track actions in a single storage zone. Sensors such as sensor 6402 amay be of any type or modality, including for example, withoutlimitation, sensors of distance, force, strain, motion, radiation,sound, energy, mass, weight, or vibration. Store cameras such as cameras6421 and 6422 may be used to identify items on which a shopper performsactions. These cameras may be mounted in the store on walls, fixtures,or ceilings, or they may be integrated into shelving unit 4210 orshelves 4212 and 4213. In one or more embodiments, ceiling cameras suchas camera 4812 may be used in addition to or instead of cameras 6421 and6422 for item identification.

Data from ceiling cameras such as 4812, from other store or shelfcameras such as cameras 6421 and 6422, and from shelf or shelving unitsensors such as 6412 and 6413 are transmitted to processor or processors130 for analysis. Processor 130 may be or may include for example one ormore store servers. In one or more embodiments, processing of image orsensor data may be performed by processing units integrated intoshelves, shelving units, or camera fixtures. These processing units mayfor example filter data or detect events, and may then transmit selectedor transformed information to one or more store servers for additionalanalysis. In one or more embodiments, processor 130 may therefore be acombination or network of processing units such as local microprocessorscombined with store servers. In one or more embodiments, some or all ofthe processing may be performed by processors that are remote from thestore.

Processor or processors 130 may analyze the data from cameras and othersensors to track shoppers, to detect actions that shoppers perform withitems or item storage areas, and to identify items that shoppers take,replace, or move. By correlating the track 5201 of a shopper with thelocation and time of actions on items, items may be associated withshoppers, for example for automated checkout in an autonomous store.

Embodiments may mix cameras and other types of sensors in variouscombinations to perform shopper and item tracking. FIG. 65 showsrelationships between analysis steps and sensors that indicate variousillustrative combinations. These combinations are non-limiting; one ormore embodiments may use any type or types of sensor data for any taskor process. Tracking of shoppers 6501 may for example use images fromstore cameras 6510, which may include any or all of ceiling cameras 6511or other cameras 6512 mounted for example on walls or fixtures.Detection 6502 of shopper's actions on items in item storage areas mayuse for example any or all of images from shelf cameras 6520 and datafrom sensors 6530 on shelves or shelving units. Shelf sensors 6530 maymeasure for example distance 6531, using for example LIDAR 6541 orultrasonic sensors 6542, or weight 6532, using for example strain gaugesensors 6543 or other scales 6544. Identification 6503 of items that ashopper removes or adds may use for example images from store cameras6510 or shelf cameras 6520. Determination 6504 of the quantity that ashopper adds or removes may use for example images from shelf cameras6520 or data from shelf sensors 6530. The possible combinationsdescribed above are not mutually exclusive, nor are they limiting.

In one or more embodiments, shelf sensors 6530 may be sensors associatedwith any type of item storage area. An item storage area may for examplebe divided into one or more storage zones, and a sensor may beassociated with each zone. In one or more embodiments, these sensors maygenerate data or signals that may be correlated with the quantity ofitems in an item storage area or a storage zone of an item storage area.For example, a weight sensor on a portion of a shelf may provide aweight signal that reflects the number of items on that portion of theshelf. Sensors may measure any type of signal that is correlated in anymanner with the quantity of items in the storage zone or entire itemstorage area. In some situations, using quantity sensors attached toitem storage zones may reduce cost and improve accuracy compared to useof cameras alone to track both shoppers and items.

FIG. 66A shows an illustrative embodiment where the storage zones arebins with a back wall that moves forward when items are removed from thebin. Shelf 4213 a is divided into four storage zones: bin 6401 a, bin6401 b, bin 6401 c, and bin 6401 d. The back walls 6601 a, 6601 b, 6601c, and 6601 d of each bin are moveable and move forward as items areremoved, and they move backward as items are added to the bin. In thisembodiment, the moveable backs of the bins move forward due to springsthat push against the backs. One or more embodiments may move the backsof the bins using any desired method. For example, in one or moreembodiments the bins may be tilted with the front end lower than theback end, and items and the back walls may slide forward due to gravity.

In the embodiment of FIG. 66A, quantity sensors 6413 are located behindthe bins of shelf 4213 a. These sensors measure the distance between thesensor and the associated moveable back of the bin. A separate sensor isassociated with each bin. Distance measurement may use any sensingtechnology, including for example, without limitation, LIDAR, ultrasonicrange finding, encoders on the walls, or cameras. In an illustrativeembodiment, sensors 6413 may be single-pixel LIDAR sensors. Thesesensors are inexpensive and robust, and provide accurate measurements ofdistance.

FIG. 66B shows a top view of the embodiment of FIG. 66A. A spring orsimilar mechanism biases each moveable back towards the front of thebin; for example, spring 6602 a pushes moveable back 6601 a towards thefront of bin 6401 a. Another type of shelf that may be used in one ormore embodiments is a gravity fed shelf, where the shelf is tilteddownwards and products are placed either on a slippery surface orrollers, so that products slide down as they are removed or pushed backas they are added. Yet another shelf type that may be used in one ormore embodiments is a motorized dispenser, where a conveyor or otherform of actuation dispenses products to the front. In all of thesecases, a distance measurement is indicative of the number of products ona particular lane or bin in a shelf, and changes in distance orperturbances in the measurement statistics are indicative of anaction/quantity. Distance measurement is illustrated for bin 6401 d.LIDAR 6402 d emits light 6403 d, which reflects off of moveable back6601 d. The time of flight 6604 d for the round trip of the light ismeasured by the sensor 6402 d, and is converted to a distance. In thisembodiment, distance signals from LIDARs 6402 a, 6402 b, 6402 c, and6402 d are transmitted to a microprocessor or microcontroller 6610,which may be integrated into or coupled to shelf 4213 a or a shelvingunit in which the shelf is installed. This processor 6610 may analyzethe signals to detect action events, and may send action data 6611 to astore server 130. This data may for example include the type of action(such as removing or adding items), the quantity of items involved, thestorage zone where the event occurred, and the time of the event. In oneor more embodiments the action detection may be performed by the storeserver 130 without a local microprocessor 6610. Embodiments may mix orcombine local processing (such as on a shelf microprocess) and storeserver processing in any desired manner.

During store operation, the quantity sensors may feed data into thesignal processor 6610 which collects statistics on quantity measurementssuch as distance, weight, or other variables, and reports as a datapacket of amount changed (distance/weight/other quantity variables) andtime of start and end of the change. The start/stop times are useful forcorrelating back to the camera images prior to and after the event.Depending on the type of shelf, it may take time for the stack ofmerchandise to advance to the front row, so it is useful to bound theevent to a range of time. If the shelf is tampered with, then thesensors may report a start event, but no matching ending event. In thiscase, the end state of the particular shelf can be inferred from thecamera images: a faulty/tempered feeder shelf will show an empty slot asthe merchandise will not feed forward. In general, camera images may beavailable in addition to the in-shelf quantity sensors, and theredundancy of sensing will enable continued operation in the event of asingle sensor being faulty or tampered with.

The event data 6611 may also indicate the storage zone (within an itemstorage area) where the even occurred. Because the 3D location in thestore of each storage zone of each item storage area may be measured orcalibrated and stored in a 3D store model, the event location data maybe correlated with shopper locations, in order to attribute item actionsto specific shopper.

One or more embodiments may incorporate a modular sensor bar that can beeasily reconfigured to accommodate different numbers and sizes ofstorage zones in a shelf, and that can be mounted easily on a shelvingfixture. A modular sensor bar may also incorporate power, electronics,and communications to simplify installation, maintenance, andconfiguration. FIG. 66C shows an illustrative modular sensor bar 6413 ethat is mounted behind a shelf 4213 e. The sensor bar 6413 has a railonto which any desired number of distance sensor units may be mountedand may be slid into position behind any storage zone or bin. Behind thefront face of the rail there may be an enclosed area containing cablingand electronics, such as a microprocessor to process signals from thedistance sensors. The configuration shown has three distance sensorunits 6402 e, 6402 f, and 6402 g. Because the item storage areas are ofdifferent widths, the distance sensor units are not evenly spaced. Ifthe store reconfigures the shelf with different sized items, distancesensor units may be easily moved to new positions, and units may beadded or removed as needed. Each distance sensor unit may for examplecontain a LIDAR that uses time-of-flight to measure the distance to theback of the corresponding storage zone.

FIG. 66D shows an image of an illustrative modular sensor bar 6413 f ina store. This sensor bar is made of a splash-proof stainless-steel metalenclosure. It attaches to existing shelving units, for example on thevertical face 6620 of the unit. The enclosure contains the processorunit or units that receive the raw signals and process the signals intoevents. Within the enclosure the microprocessor may for example transmitthe signals via USB or Ethernet to a store server. The individualdistance sensor units, such as unit 6402 h, are black plastic carriersthat contain the sensors and that slide along the bar enclosure. Theycan be positioned anywhere along the bar to match the dimensions of thefeeder lanes containing the merchandise. In this configuration, sensorsmay be easily moved to accommodate narrower and wider objects and theirstorage zones, and the carriers can be locked in place once the shelf isconfigured. The distance sensor units may have a glass front (forcleanability) and a locking mechanism. The wires from the sensor unitsto the processor are fed into the enclosure through a slot at the bottomof the steel enclosure so as to avoid any liquid accumulation and allowany splashed liquid to flow away from the electronics.

FIG. 67 illustrates conversion of the distance data 6701 from a LIDAR(or other distance sensor) into the quantity of items in a storage zone6702. As items are removed from the storage zone, the moveable backmoves further away from the sensor; therefore quantity 6702 variesinversely with distance 6701. The slope of the line relating distanceand quantity depends on the size of the items in the bin; for example,if soda cans have a smaller diameter than muffins, then line 6703 forsoda cans lies above line 6704 for muffins. Therefore, determining thequantity of items in a storage zone from the distance 6701 may requireknowledge of the types of items in each zone. This information may beconfigured when a storage area is set up or stocked, or it may bedetermined using image analysis, for example as described below withrespect to FIG. 72A.

FIG. 68 illustrates action detection based on changes in distancesignals 6802 over time 6801 from the embodiment illustrated in FIGS. 66Aand 66B. This detection may be performed for example by a microprocessor6601, by a store server 130, or by a combination thereof. Smallfluctuations in the distance signals 6802 may be due to noise; thus theymay be filtered out for example by a low pass filter. Large changes thatdo not revert quickly may indicate addition or removal of items to anassociated storage zone. For example, change 6803 in signal 6811 c isdetected as action 6804 in storage zone 6401 c, and change 6805 insignal 6811 b is detected as action 6806 in storage zone 6401 b. Theaction signals 6804 and 6806 may indicate for example the action type(addition or removal for example), the quantity of items involved, thetime the action occurred, and the storage zone where the actionoccurred. The time of an action may be a time range during which thedistance measurements were changing significantly; the start and stoptimes of this time range may be correlated with camera images (a “beforeaction” image prior to the start time, and an “after action” image afterthe stop time) to classify the item or to further characterize theaction.

FIGS. 69A and 69B illustrate a different shelf embodiment 4213 b thatuses a different type of storage zone sensor to detect quantity changesand shopper actions. This embodiment may be used for example withhanging merchandise, such as items in bags. A storage zone in thisembodiment corresponds to a hanging rod onto which one or more items maybe placed. Shelf or rack 4213 b has four hanging rods 6901 a, 6901 b,6901 c, and 6901 d. Associated with each rod are sensors that measurethe weight of the items on the rod; this weight is correlated with thenumber of items on the rod. FIG. 69B shows a side view of rod 6901 b,and it illustrates the weight measurement calculations. The rod issupported by two elements 6911 and 6912. These two elements provideforces that keep the rod in static equilibrium. Strain gauges (or othersensors) 6913 and 6914 may measure the forces 6931 and 6932,respectively, exerted by elements 6911 and 6912. The individual forces6931 and 6932 vary with the weight of the items on the rod and with thelocation of these items; however, the difference between forces 6931 and6932 varies only with the mass of the rod and the items. This forcedifference must equal the total weight 6930 due to the mass 6922 of therod and the masses such as 6921 a, 6921 b, and 6921 c of the itemshanging from the rod. Calculations 6940 therefore derive the quantity kof items on the rod based on known quantities such as per item mass androd mass, and on the strain gauge sensor signals. This arrangement ofstrain gauges 6913 and 6914, and the calculations 6940 are illustrative;one or more embodiments may use two (or more strain gauges) in anyarrangement, and may combine their readings to derive the mass of items,and therefore the quantity of items, hanging from the rod.

FIGS. 70A and 70B show another illustrative embodiment of item storagearea 4213 c divided into bins 7001 a, 7001 b, and 7001 c, each of whichhas one or more associated weight sensors to weigh the contents of thebin. FIG. 70B shows a side view of bin 7001 a, which is supported by twoelements with strain gauges 7002 a and 7002 b. Use of two strain gaugesis illustrative; one or more embodiments may use any number of straingauges or other sensors to weigh a bin. The sum of the forces measuredby these two strain gauges matches the weight of the bin plus itscontents. A calculation similar to calculation 6940 of FIG. 69B may beused to determine the number of items in the bin. One or moreembodiments may weigh bins using any type of sensor technology,including but not limited to strain gauges. Any type of electronic ormechanical scale may be used, for example.

A potential benefit of shelves with integrated or coupled quantitysensors is that shelves may be packed closely together, since cameraslooking down on shelf contents may not be needed to detect actions or todetermine quantities. It may be sufficient to have cameras that canobserve the front of each storage area, when they are combined withquantity sensors associated with storage zones or item storage areas.This scenario is illustrated in FIG. 71, which shows three shelves 4213aa, 4213 ab, and 4213 ac stacked on top of one another, providing a highdensity of products in a small space, with a separation 7103 betweenshelves that may be only slightly greater than the height of the items.The shelves include quantity sensors (such as the sensors illustrated inFIGS. 66A and 66B); therefore, it may not be necessary to havedownward-facing cameras on the bottoms of the shelves to observe theshelf below. Instead other cameras in the store, such as cameras 7101and 7102, may be oriented to observe the front face of each item storagezone. These other cameras may be mounted on walls, ceilings, orfixtures, or they may be integrated into a shelving unit that containsthe storage zones. Any number of cameras may be used to observe thefront faces of item storage zones. In addition to increasing the packingdensity of products, this arrangement may reduce cost by replacingrelatively expensive cameras on the bottoms of shelves with inexpensivequantity sensors (such as single-pixel LIDARs). Having multiple camerasobserve the shelf from different viewpoints provides the advantage thatan unoccluded view may be available of any point in the shelf from atleast one camera. (This benefit is further described below with respectto FIG. 73.)

FIG. 72A illustrates use of images from cameras 7101 and 7102 toidentify items taken from or replaced into item storage zones. An action7201 of taking an item is detected by a quantity sensor associated witha storage zone in shelf 4213 ac. This action generates a signal 7202(for example from a microprocessor in the shelf), that provides theaction, the storage area and storage zone affected, the time, andpotentially the quantity of items. This signal is received by a storeserver 130. The store server 130 then obtains images from cameras 7101and 7102, and uses these images to identify the item or items affected.Since the action signal 7202 indicates that one or more items have beentaken, the server needs to obtain “before” images of the affectedstorage zone prior to the action. (If the action had indicated that anitem had been added, the server would obtain “after” images of theaffected storage zone after the action). The server may then projectthese images onto a vertical plane 7203 that corresponds to the front ofthe item storage area. This projection may be done for example asdescribed with respect to FIG. 33, except that the projection here is toa vertical plane rather than to a horizontal plane as in FIG. 33. Byprojecting images from multiple cameras onto a common plane at the frontof the item storage area, distortions due to differences in camerapositions and orientations are minimized; camera images may therefore becombined to identify the items at the front of each storage zone.Additionally, by re-projecting all camera views to this plane, we canhave all cameras agree on the view of a shelf. The projected view is 1:1with the physical geometry of the shelf; a pixel in the image XY spacelinearly corresponds to a point in the shelf XZ plane, and each pixelhas a physical dimension. Reprojections reduces the amount of trainingrequired for an item classifier and simplifies visual detection andclassification of products. This projection process 7204 may result forexample in an image such as image 7205, from one or more of the cameras.Because the action signal 7202 identifies the affected storage zone, theregion 7207 of the image 7205 that corresponds to this zone may beextracted in step 7206, resulting in a single item image 7208. Thisimage may then be input into a classifier 6203, which outputs the itemidentity 7209. One or more embodiments may use any type of imageclassifier, such as for example a neural network trained on labelleditem images. Classifier 6203 may be trained on data, it may beengineered to recognize images or features, or it may have a combinationof trained and engineered components. Trained classifiers or trainedclassifiers may use any type of machine learning technologies, includingbut not limited to neural networks. Any system or combination of systemsthat performs visual identification of items may be used as a classifierin one or more embodiments. The item identity 7209 may then be combinedwith data 7202 for the action, and with the shopper information based onshopper tracking, to make the association 7210 of the shopper with theitem, action, quantity, and time. As described above, shopper trackingindicates for example which field of influence volume associated with ashopper intersects the item storage zone where and when the actionoccurs.

FIG. 72B shows images from a store that illustrate projection of imagesfrom different cameras to a common front vertical plane. Images 7221 and7222 are views of a shelving unit from two different cameras. Images ofitems are in different positions in these images; for example, therightmost front item on the second shelf from the top is at pixellocation 7223 in image 7221, but position 7224 in image 7222. Theseimages are projected onto the front plane of the shelving unit (asdescribed above with respect to FIG. 72A), resulting in projected images7231 and 7232. The products at the fronts of the shelves are then in thesame pixel locations in both images. For example, the rightmost frontitem on the second shelf from the top is at the same location 7233 and7234 in the images 7231 and 7232, respectively.

In one or more embodiments, shopper tracking may be used as well todetermine which camera view or views may be used to identify items.Although cameras may be positioned and oriented to view the front planeof an item storage area, shoppers may occlude some of the views if ashopper is located between the affected items and the cameras. Becausethe person tracking process 7300 tracks the location of the shoppers asthey move through the store, the field of influence volume 1001 of ashopper may also be projected onto the front plane from the perspectiveof each camera; these projections indicate which cameras haveunobstructed views of an affected item storage zone, spanning the timesof the detected event from the distance/weight sensing. For example,projection 7302 of the field of influence volume 1001 onto the frontplane 7203 from the perspective of camera 7102 results in region 7311 b,which does not occlude the affected image region 7207 of the itemstorage zone where an item was removed. In contrast, projection 7301from the perspective of camera 7101 shows that field of influence volume1001 is projected to region 7311 a, which does obstruct the view ofregion 7207. Therefore, in this scenario item classification may useonly the image 7205 b, and not the image 7205 a. In general, multiplecameras may be configured to observe a storage area from multipledifferent perspectives, so that at least on un-occluded view of thefront of the storage area is available to classify products.

While the invention herein disclosed has been described by means ofspecific embodiments and applications thereof, numerous modificationsand variations could be made thereto by those skilled in the art withoutdeparting from the scope of the invention set forth in the claims.

What is claimed is:
 1. A camera-based tracking and authorizationextension system comprising: a processor configured to obtain a 3D modelof an area, wherein said area comprises a first location where acredential receiver is located; and a second location, different fromsaid first location, where an item storage area is located; receive afirst sequence of images captured at a corresponding sequence of timesduring a first time period from cameras in said area, wherein at least afirst camera of said cameras is oriented to view said first location;and, at least a second camera of said cameras is oriented to view saidsecond location; project said first sequence of images onto a plane insaid area, to form a sequence of projected images; analyze said sequenceof projected images and said 3D model of said area to determinelocations of people in said area at said sequence of times; receive anauthorization based on a credential provided by a person to saidcredential receiver at a first time of said sequence of times duringsaid first time period; associate said authorization with said person;calculate a position of said person at each time of said sequence oftimes, wherein said position of said person at said first time is at orproximal to said first location where said credential receiver islocated; said position of said person at said each time is a location ofsaid locations of people in said area at said each time; when a 3D fieldof influence volume around said position of said person at a second timeof said sequence of times intersects said item storage area, obtainsensor data from said item storage area over a second time periodcontaining said second time; analyze said sensor data to identify anitem taken from said item storage area during said second time period;and, associate said item taken from said item storage area with saidauthorization associated with said person, and, grant access by saidperson to said item storage area at said second time based on saidauthorization.
 2. The system of claim 1, wherein said analyze saidsequence of projected images comprises for each time in said sequence oftimes during said first time period, subtract a background image fromeach projected image of said sequence of projected images captured atsaid each time to form a corresponding plurality of masks at said eachtime, each mask of said plurality of masks corresponding to a camera ofsaid cameras; combine said plurality of masks at said each time to forma combined mask at said each time; and, identify one or more regions insaid combined mask at said each time as said locations of people in saidarea at said each time.
 3. The system of claim 2, wherein said one ormore regions in said combined mask comprise shapes corresponding to anexpected cross-sectional size of said person.
 4. The system of claim 1,wherein said credential comprises one or more of a credit card, a debitcard, a bank card, an RFID tag, a mobile payment device, a mobile walletdevice, an identity card, a mobile phone, a smart phone, a smart watch,smart glasses or goggles, a key fob, a driver's license, a passport, apassword, a PIN, a code, a phone number, or a biometric identifier. 5.The system of claim 1, wherein said credential comprises a form ofpayment linked to an account associated with said person; and, saidauthorization comprises an authorization to charge purchases by saidperson to said account.
 6. The system of claim 5, wherein said processoris further configured to charge a purchase of said item taken from saiditem storage area to said account.
 7. The system of claim 1, whereinsaid grant access comprises transmit a command to a controllable barrierto allow access to said item storage area by said person.
 8. The systemof claim 7, wherein said item storage area is in a case; saidcontrollable barrier comprises a door to said case.
 9. The system ofclaim 7, wherein said item storage area is in a building; saidcontrollable barrier comprises a door to all or a portion of saidbuilding.
 10. The system of claim 1, wherein said processor is furtherconfigured to further analyze said sensor data to determine a quantityof items removed from said item storage area by said person.
 11. Thesystem of claim 1, wherein said sensor data from said item storage areacomprises a second sequence of images of said item storage area capturedduring said second time period.
 12. The system of claim 11, wherein saidanalyze said sensor data to identify an item taken from said itemstorage area during said second time period comprises compare one ormore images of said second sequence of images captured at a beginning ofsaid second time period to one or more images of said second sequence ofimages captured at an end of said second time period to identity changesin said item storage area.
 13. The system of claim 12, wherein saidanalyze said sensor data to identify an item taken from said itemstorage area during said second time period further comprises input saidchanges in said item storage area into a classifier to identify saiditem taken from said item storage area.
 14. The system of claim 13,wherein said classifier comprises a neural network.
 15. The system ofclaim 1, wherein said analyze said sequence of projected imagescomprises for each time in said sequence of times during said first timeperiod, input said projected images captured at said each time into amachine learning system that outputs an intensity map, wherein saidintensity map comprises a likelihood at each location of said locationsthat one or more persons are at said each location of said locations.16. The system of claim 15, wherein said analyze said sequence ofprojected images further comprises for each time in said sequence oftimes during said first time period, further input into said machinelearning system a position map corresponding to each camera of saidcameras in said area, wherein a value of said position map at a locationon said plane is a function of a distance between said location on saidplane and said each camera.
 17. The system of claim 1, wherein said 3Dfield of influence volume comprises a standardized shape centered atsaid position of said person at said second time.
 18. The system ofclaim 17, wherein said standardized shape comprises a cylinder.
 19. Thesystem of claim 18, wherein a height and a radius of said cylinder arebased on an apparent size of said person in said first sequence ofimages.
 20. The system of claim 1, wherein said plane is a horizontalplane.
 21. The system of claim 1, wherein said plane is a non-horizonalplane.
 22. The system of claim 1, wherein said sensor data comprisesimage data.
 23. The system of claim 1, wherein said sensor datacomprises non-image data.
 24. A camera-based tracking and authorizationextension system comprising: a processor configured to obtain a 3D modelof an area, wherein said area comprises a first location where acredential receiver is located; and a second location, different fromsaid first location, where an item storage area is located; receive afirst sequence of images captured at a corresponding sequence of timesduring a first time period from cameras in said area, wherein at least afirst camera of said cameras is oriented to view said first location;and, at least a second camera of said cameras is oriented to view saidsecond location; project said first sequence of images onto a plane insaid area, to form a sequence of projected images; analyze said sequenceof projected images and said 3D model of said area to determinelocations of people in said area at said sequence of times; receive anauthorization based on a credential provided by a person to saidcredential receiver at a first time of said sequence of times duringsaid first time period; associate said authorization with said person;calculate a position of said person at each time of said sequence oftimes, wherein said position of said person at said first time is at orproximal to said first location where said credential receiver islocated; said position of said person at said each time is a location ofsaid locations of people in said area at said each time; when a 3D fieldof influence volume around said position of said person at a second timeof said sequence of times intersects said item storage area, obtainsensor data from said item storage area over a second time periodcontaining said second time; analyze said sensor data to identify anitem taken from said item storage area during said second time period;and, associate said item taken from said item storage area with saidauthorization associated with said person; wherein said analyze saidsequence of projected images comprises for each time in said sequence oftimes during said first time period, input said projected imagescaptured at said each time into a machine learning system that outputsan intensity map, wherein said intensity map comprises a likelihood ateach location of said locations that one or more persons are at saideach location of said locations.
 25. The system of claim 24, whereinsaid analyze said sequence of projected images further comprises foreach time in said sequence of times during said first time period,further input into said machine learning system a position mapcorresponding to each camera of said cameras in said area, wherein avalue of said position map at a location on said plane is a function ofa distance between said location on said plane and said each camera. 26.A camera-based tracking and authorization extension system comprising: aprocessor configured to obtain a 3D model of an area, wherein said areacomprises a first location where a credential receiver is located; and asecond location, different from said first location, where an itemstorage area is located; receive a first sequence of images captured ata corresponding sequence of times during a first time period fromcameras in said area, wherein at least a first camera of said cameras isoriented to view said first location; and, at least a second camera ofsaid cameras is oriented to view said second location; project saidfirst sequence of images onto a plane in said area, to form a sequenceof projected images; analyze said sequence of projected images and said3D model of said area to determine locations of people in said area atsaid sequence of times; receive an authorization based on a credentialprovided by a person to said credential receiver at a first time of saidsequence of times during said first time period; associate saidauthorization with said person; calculate a position of said person ateach time of said sequence of times, wherein said position of saidperson at said first time is at or proximal to said first location wheresaid credential receiver is located; said position of said person atsaid each time is a location of said locations of people in said area atsaid each time; when a 3D field of influence volume around said positionof said person at a second time of said sequence of times intersectssaid item storage area, obtain sensor data from said item storage areaover a second time period containing said second time; analyze saidsensor data to identify an item taken from said item storage area duringsaid second time period; and, associate said item taken from said itemstorage area with said authorization associated with said person;wherein said 3D field of influence volume comprises a standardized shapecentered at said position of said person at said second time; and,wherein said standardized shape comprises a cylinder.
 27. The system ofclaim 26, wherein a height and a radius of said cylinder are based on anapparent size of said person in said first sequence of images.
 28. Acamera-based tracking and authorization extension system comprising: aprocessor configured to obtain a 3D model of an area, wherein said areacomprises a first location where a credential receiver is located; and asecond location, different from said first location, where an itemstorage area is located; receive a first sequence of images captured ata corresponding sequence of times during a first time period fromcameras in said area, wherein at least a first camera of said cameras isoriented to view said first location; and, at least a second camera ofsaid cameras is oriented to view said second location; project saidfirst sequence of images onto a plane in said area, to form a sequenceof projected images, wherein said plane is a non-horizonal plane;analyze said sequence of projected images and said 3D model of said areato determine locations of people in said area at said sequence of times;receive an authorization based on a credential provided by a person tosaid credential receiver at a first time of said sequence of timesduring said first time period; associate said authorization with saidperson; calculate a position of said person at each time of saidsequence of times, wherein said position of said person at said firsttime is at or proximal to said first location where said credentialreceiver is located; said position of said person at said each time is alocation of said locations of people in said area at said each time;when a 3D field of influence volume around said position of said personat a second time of said sequence of times intersects said item storagearea, obtain sensor data from said item storage area over a second timeperiod containing said second time; analyze said sensor data to identifyan item taken from said item storage area during said second timeperiod; and, associate said item taken from said item storage area withsaid authorization associated with said person.